Materials for Architects and Builders

12

PLASTER AND BOARD
MATERIALS

CONTENTS

Introduction 384 Accessories for plastering 389
Gypsum plaster 384 Gypsum floor screed 390
384 Fire resistance of plaster materials 390
Manufacture of gypsum plaster 385 Recycling gypsum products 390
Types of plaster 386 Lime plaster 391
Backgrounds for plaster 386 Calcium silicate boards 391
Plasterboard 387 References 391
Special plasters

Introduction

Plastering, based on lime, was brought to Britain by the support for plasters was interwoven hazel twigs, but by
Romans. In Britain, it was originally used to strengthen the fifteenth century split timber laths were common.
and seal surfaces and, in the case of combustible The modern equivalent is the use of galvanised and
materials, to afford some fire protection, but by the stainless steel expanded metal.
eighteenth century its value as a decorative finish had
been appreciated. The use of gypsum plaster both as a Gypsum plaster
sealant and as a decorative material by the Minoan
civilisation is well documented, and current UK prac- MANUFACTURE OF GYPSUM PLASTER
tice is now based on gypsum (hydrated calcium
sulphate), rather than lime. Gypsum is mined from Rock gypsum is mined, crushed and ground to a fine
geological deposits produced by the gradual evapora- powder. The natural mineral may be white or dis-
tion of lakes containing the mineral; there are extensive coloured pale pink, grey or brown due to small quan-
reserves within the UK, mainly in the North of England, tities of impurities, which do not otherwise affect the
but also in the East Midlands. product. On heating to temperatures in the range
130–170°C, water is driven off the hydrated gypsum;
Historically, fibrous materials have been used to the type of plaster produced is largely dependent upon
reinforce plaster and particularly to control shrinkage the extent of this dehydration process.
in lime plaster. Traditionally, ox, horse and goat hair
were the standard materials; however, straw, hemp
and jute have also been used. The earliest lightweight

PLASTER AND BOARD MATERIALS 385

130°C 170°C C Gypsum plaster for special purposes
CaSO4·2H2O ⎯→ CaSO4·1⁄2H2O C1 Gypsum plaster for fibrous plasterwork
⎯→ CaSO4 C2 Gypsum mortar
hydrated hemihydrate anhydrous C3 Acoustic plaster
C4 Thermal insulation plaster
gypsum gypsum C5 Fire protection plaster
C6 Thin-coat plaster, finishing product
Gypsum plasters including those for special purposes C7 Finishing product
are defined in the standard BS EN 13279–1: 2008.
Gypsum plasterboards are defined in BS EN 520: 2004.

TYPES OF PLASTER Undercoat and one-coat plasters
The main constituents of undercoat and one-coat
Plaster of Paris plasters are retarded hemi-hydrate gypsum, with light-
weight aggregates for the lightweight products, to-
Plaster of Paris is produced by driving off three- gether with small quantities of limestone, anhydrite
quarters of the water content from natural hydrated (anhydrous gypsum), clay and sand. In addition, other
gypsum. Plaster of Paris sets very quickly on the materials are incorporated to adjust the product
addition of water, and is therefore often used as a specification and setting time, which normally ranges
moulding material. between one and two hours. Thus, lime is added to
undercoat plaster, and for backgrounds of high suction,
Retarded hemi-hydrate gypsum plaster a water-retention agent is also required. For example,
browning is suitable for use on backgrounds with
The majority of plasters in current use within con- moderate or high-suction and a good mechanical
struction are based on retarded hemi-hydrate gypsum. key (e.g. brickwork and blockwork), but on smooth
The addition of different quantities of a retarding surfaces or low-suction backgrounds such as concrete,
agent, usually keratin, is used to adjust the setting an initial bonding coat is required. For higher impact
time (usually between 1.5 and 2 hours) for different resistance, cement and granulated blast furnace slag are
products. Other additives and admixtures include incorporated, and for a one-coat plaster, limestone is
fillers, fibres, lime, lightweight aggregates, pigments, added. Typical applications for walls would be 11 mm
retarders and plasticisers. for undercoats with a finish coat of 2 mm, or a single
one-coat application of 13 mm. The undercoat for
Types of gypsum binders and plasters (BS EN 13279–1: ceilings would normally be 8 mm with a 2 mm-finish
2008): coat. A maximum total plaster thickness of 25 mm is
recommended.
Notation Designation
Finish-coat plasters
A Gypsum binder for further processing For finish-coat plasters, like undercoat plasters, the
A1 Gypsum binders for direct use main constituent is retarded hemi-hydrate gypsum,
A2 Gypsum binders for direct use on site but with a small addition of lime to accelerate the set.
A3 Gypsum binders for further processing The lightweight products contain exfoliated vermic-
B Gypsum plaster ulite. Finish coats on masonry substrates are usually
B1 Gypsum building plaster 2 mm in thickness, and board finish plaster is normally
B2 Gypsum-based building plaster applied to 2–3 mm.

(minimum 50% gypsum) Lightweight plasters
B3 Gypsum-lime building plaster Lightweight plasters usually contain inorganic ex-
panded perlite or exfoliated vermiculite, but organic
(>5% lime) lightweight aggregates may also be used. Premixed
B4 Lightweight gypsum building plaster expanded polystyrene dry plaster/mortar for thermal or
impact noise insulation is described in BS EN 16025:
(inorganic or organic aggregates) 2013. The range of densities and associated thermal
B5 Lightweight gypsum-based building conductivities is listed in Table 12.1.

plaster
B6 Lightweight gypsum-lime building

plaster
B7 Enhanced surface hardness gypsum

plaster

386 PLASTER AND BOARD MATERIALS

Table 12.1 Typical relationship between density and thermal driven in straight, leaving a shallow depression but
conductivity for gypsum plasters without fracturing the paper surface. Alternatively
boards may be screwed. Standard thicknesses are 12.5,
Density Thermal conductivity 15 and 19 mm, although 9.5 mm board may also be
(kg/m3) (W/m K) obtained.

600 0.18 Only the moisture-resistant grades of plasterboard
700 0.22 (Type H) normally require the application of a bond-
800 0.26 ing agent before plastering. These have a water-resistant
900 0.30 core and treated liners, so may be used in moist and
1000 0.34 humid conditions such as kitchens or bathrooms
1100 0.39 and behind external finishes such as vertical tiling and
1200 0.43 weatherboarding, or in external sheltered positions
1300 0.47 protected from direct rain.
1400 0.51
1500 0.56 Fire-resistant boards (Type F), available in 12.5 and
15 mm thicknesses and reinforced with glass fibres,
BACKGROUNDS FOR PLASTER offer increased fire resistance over standard gypsum
boards. Fire-resistant boards are colour-coded pink.
Plaster bonds to the background by a combination of Impact-resistant boards are also reinforced with glass
mechanical key and adhesion. Backgrounds should fibres and have a high-strength paper liner. Glassfibre-
be clean, dry and free from other contamination, and reinforced gypsum is described in Chapter 11.
the specification of the plaster should be appropriate
to the suction of the background surface. Where Sound insulation boards, colour-coded blue, have a
possible, as in the case of brickwork, a good mechanical modified gypsum core, making them heavier than
key should be obtained by raking out the joints. On standard wallboards. The extra weight enhances the
hard, low-suction materials such as smooth concrete sound attenuation by up to 5 dB Rw compared to
and ceramic tiles, a polyvinyl acetate (PVA) or pro- standard gypsum board. When used in conjunction
prietary bonding agent should be applied. Similarly, to with Robust Details, sound insulation boards provide
control the high suction in substrates such as aerated enhanced acoustic performance. The Approved Docu-
concrete blocks, a bonding agent may be applied or the ment – Building Regulations Part E – Resistance to the
substrate wetted prior to the application of plaster. Passage of Sound requires a surface mass of 10 kg/m2
Plaster may, however, be applied directly to dense for plasterboard separating and internal walls as well as
aggregate concrete blocks without prior wetting. Where floors.
two or more coats of plaster are applied, the undercoats
should be scratched to ensure good subsequent bond- The heavy 19 mm gypsum planks, produced to a
ing. Gypsum plasters, if applied correctly, do not shrink width of 600 mm, are used in walls, ceilings and floors
or crack on drying out and subsequent coats may be to comply with the requirements of the Building
applied in quick succession. Regulations when constructed according to Robust
Details.
PLASTERBOARD
Boards are available finished with PVC, backed with
Plasterboard consists of a gypsum core bonded to aluminium foil or laminated to insulation (expanded
strong paper liners. Most wallboards have one light polystyrene, extruded polystyrene, phenolic foam or
surface for direct decoration or plaster skim and one mineral wool) for increased thermal properties. (The
grey surface. The decorative surface may be either thermal conductivity of standard plasterboard is 0.19
tapered or square. The standard board sizes are 1200 W/m K.)
and 900 mm wide to coordinate with timber or metal
stud partitioning systems. Plasterboard may be cut with Types of plasterboards (BS EN 520: 2004):
a saw or scored and snapped. Nail fixings should be
Type Designation
A
Gypsum plasterboard with a face
H1, H2, suitable for a gypsum finish coat or
H3 decoration

Gypsum plasterboard with reduced
water absorption rates

PLASTER AND BOARD MATERIALS 387

E Gypsum sheathing board for external Natural fibre-reinforced gypsum boards are manu-
walls but not permanently exposed to factured from cellulose fibres, frequently from recycled
weather conditions paper, or wood fibres within a matrix of gypsum.
The boards may be uniform with dispersed fibres
F Gypsum plasterboard with improved or laminated with woven or non-woven gypsum-
core cohesion at high temperatures reinforced sheets encasing a perlite and gypsum core.
Boards are impact and fire resistant and easily fixed
P Gypsum baseboard to receive gypsum by nails, screws, staples or adhesive as a dry-lining
plaster system to timber, metal framing or masonry. Standard
boards are 1200 ϫ 2400 mm with thicknesses normally
D Gypsum plasterboard with controlled in the range 12.5–18 mm. Joints are filled or taped
density and corners beaded as for standard plasterboard pro-
ducts. A composite board of fibre-reinforced gypsum
R Gypsum plasterboard with enhanced and expanded polystyrene offers enhanced insulation
strength properties. Gypsum boards with fibrous reinforcement
are defined in BS EN 15283: 2008. (The thermal
I Gypsum plasterboard with enhanced conductivity of gypsum board containing 13% wood
surface hardness fibres is 0.24 W/m K.)

Note: Some boards may combine more than one Types of gypsum boards with fibrous reinforcement
designation. (BS EN 15283: 2008):

Plasterboard systems Type Designation
GM
Plasterboard non-load-bearing internal walls may Gypsum board with mat reinforcement
be constructed using proprietary metal stud systems ·GM-H1 Gypsum board with mat reinforcement
or as traditional timber stud walls. Where appro-
priate, acoustic insulation should be inserted within the GM-H2 and reduced water absorption rate
void spaces. Dry-lining to masonry may be fixed with GM-I Gypsum board with mat reinforcement
dabs of adhesive, or alternatively with metal or timber
framing. Plasterboard suspended ceiling systems are GM-R and enhanced surface hardness
usually supported on a lightweight steel framework Gypsum board with mat reinforcement
fixed directly to either concrete or timber. Convex and GM-F
concave surfaces can be achieved. Sound transmission and enhanced strength
through existing upper-storey timber-joist floors can GF Gypsum board with mat reinforcement
be reduced by a combination of resiliently mounted GF-H
plasterboard and mineral wool insulation. Compliance and enhanced core cohesion at high
with the acoustic requirements of the Building Regula- ·GF-W1 temperatures
tions Approved Document E for domestic building Gypsum fibre board
can be achieved using Robust Details. Components GF-W2 Gypsum fibre board with reduced water
for plasterboard metal-framing systems are defined in GF-D absorption rate
BS EN 14195: 2005. Gypsum fibre board with reduced
GF-I surface water absorption rate
Plasterboard ceiling tiles Gypsum fibre board with enhanced
Plasterboard ceiling tiles are available in a range of ·GF-R1 density
smooth, textured and perforated finishes to produce Gypsum fibre board with enhanced
various levels of sound-insulating and sound-absorbing GF-R2 surface hardness
properties. The standard tiles are 600 ϫ 600 mm, Gypsum fibre board with enhanced
for fixing to metal sub-framing. Fire classification is strength
Class 0 and Euroclass A2-s1, d0.

Fibre-reinforced gypsum boards SPECIAL PLASTERS

Fibre-reinforced gypsum boards are manufactured with Renovating plaster
either natural or glass fibres. Glassfibre-reinforced Renovating plaster is used where walls have been
gypsum (GRG) is described in Chapter 11. stripped of existing plaster during the successful

388 PLASTER AND BOARD MATERIALS

installation of a new damp-proof course. Renovating can be achieved. The textured surface may be left as a
plasters contain aggregates which promote surface natural white finish or painted as required.
drying when applied to structures with residual
moisture, but they should not be used in permanently Polished plaster
damp locations below ground level. Renovating plaster
should also not be used where masonry is heavily Polished plaster is usually applied in three coats over a
contaminated with salts, such as in buildings not primer. The first coat is not tinted, but the subsequent
originally constructed with damp-proof courses, and coats are pigmented to the required colour. Coats are
on the brickwork of chimney breasts. Renovating applied with stainless steel tools allowing 10 hours’
plasters contain a fungicide to inhibit mould growth drying time between coats. The final coat is polished
during the drying-out process. within 5–10 minutes of its application to give the
required smooth and hard surface. After 48 hours a wax
Projection plaster finish is applied and polished to produce the required
highly reflective surface finish.
Projection plaster is sprayed onto the background from
a projection machine as a continuous ribbon which Fibrous plaster
flows sufficiently for the ribbons to coalesce. The plaster
should be built up to the required thickness, ruled to Fibrous plaster is Plaster of Paris reinforced with jute,
an even surface, then flattened and trowelled to a flat sisal, hessian, glass fibres, wire mesh or wood laths. It
surface. As with all plastering the process should not is used for casting in moulds, ornate plasterwork, such
be carried out under freezing, excessively hot or dry as fire surrounds, decorative cornices, dados, friezes,
conditions. A typical application to masonry would be panel mouldings, corbels and centre-pieces for ceilings
13 mm and should not exceed 25 mm. in both restoration and new work. The reinforcement
material may be elementary in the form of random
Acoustic plaster fibres or sheet material, or complementary as softwood
laths or lightweight steel sections. Fibrous plaster is
Acoustic plaster has a higher level of sound absorption described in the standards BS EN 13815: 2006 and BS
than standard gypsum plasters owing to its porosity EN 15319: 2007.
and surface texture. Aluminium powder is added to the
wet plaster mix to produce fine bubbles of hydrogen Phase change material plaster
gas, which remain trapped as the plaster sets giving it
a honeycomb structure. One form of acoustic plaster- An alternative method of stabilising internal room
board consists of perforated gypsum plasterboard temperatures, rather than using thermal mass, is to
which may be backed with a 100 mm glass wool sound- incorporate phase change materials (PCMs) into
absorbing felt. the building fabric. One approach is to use a layer
of gypsum plaster containing 26–30% by volume of
X-ray plaster phase change material. A commercial system uses
wax encapsulated within 3 μm particles of PVA,
X-ray plaster is retarded hemi-hydrate plaster con- which are formed as dispersion, and then dried to a
taining barium sulphate (barytes) aggregate. It is used 0.1–0.3 mm powder for mixing into gypsum. The wax
as an undercoat plaster in hospitals, etc., where pro- undergoes a phase change at 23°C or 26°C, absorbing
tection from X-rays is required. Typically, a 20 mm heat as it melts and releasing it as it solidifies. A 30 mm
layer of X-ray plaster affords the same level of pro- layer of phase change gypsum plaster has an equivalent
tection as a 2 mm sheet of lead, providing that it is free thermal stabilising effect to a mass of 180 mm of
of cracks. concrete or 230 mm of brickwork, and a 15 mm PCM
gypsum board is equivalent to 100 mm of concrete. The
Textured plaster boards may be used for ceilings or wall linings as
appropriate, and the phase change temperature should
Textured plaster is frequently applied to plasterboard be specified. Current costs are of the order of 10 times
ceilings. A variety of different patterns and textures that of standard plasterboard.

PLASTER AND BOARD MATERIALS 389

VOC absorbing plasterboard ACCESSORIES FOR PLASTERING

Formaldehyde and other VOCs are absorbed into Beads
gypsum boards or tiles and converted into inert com-
pounds which remain trapped, preventing re-emission. Angle and stop beads are manufactured from gal-
Internal air quality is therefore maintained at a higher vanised or stainless perforated steel strip or expanded
level by the removal of approximately 70% of the metal. They provide a protected, true straight arris
organic pollutants. or edge with traditional plastering to masonry or for

Fig. 12.1 Plastering beads and arch formers

390 PLASTER AND BOARD MATERIALS

thin-coat plasterboard. Proprietary systems are manu- than 2% cement, may be used as an alternative to a
factured similarly from perforated galvanised or stain- traditional sand and cement screed, provided that a
less steel to form movement joints in dry-lining systems floor covering is to be used. The material is self-
(Fig. 12.1). These components are defined in BS EN smoothing and may be pumped. It is laid on a poly-
14353: 2007 and BS EN 13658: 2005. thene membrane to a minimum thickness of 35 mm
for floating screeds, and may be used over under-
Scrim and jointing tape floor heating systems. When set, the hard plaster has a
minimum 28-day compressive strength of 30 MPa.
Scrim, an open-weave material, is used across joints
between plasterboards and in junctions between plaster FIRE RESISTANCE OF PLASTER MATERIALS
and plasterboard. Both self-adhesive glass fibre mesh
and traditional jute scrim are available. For the Gypsum products afford good fire protection within
prevention of thermal movement cracking at plaster- buildings due to their basic chemical composition.
board butt joints, 50 mm paper tape bedded into the Gypsum, hydrated calcium sulphate (CaSO4·2H2O) as
plaster skim is often more effective than self-adhesive present in plaster and plasterboard, contains nearly
scrim. The paper-based tape and bedding compounds 21% water of crystallisation. When exposed to a fire
for plasterboards are defined in BS EN 14353: 2007. this chemically combined water is gradually expelled
in the form of vapour. It is this process which absorbs
Coves and cornices the incident heat energy from the fire, considerably
reducing the transmission of heat through the plaster,
Decorative coves and cornices are manufactured from thus protecting the underlying materials. The process
gypsum plaster encased in a paper liner. In some of dehydrating the gypsum commences on the face
cases the gypsum is reinforced with glass fibres. The adjacent to the fire, and immediately the dehydrated
components (Fig. 12.2) can be cut to size with a saw, material, because it adheres to the unaffected gypsum,
and are normally fixed with proprietary adhesives. The acts as an insulating layer slowing down further
standard sizes of plain cove are 100 mm and 127 mm, dehydration. Even when all the water of crystallisation
although a wide variety of decorative forms are also has been expelled, the remaining anhydrous gypsum
produced. continues to act as an insulating layer while it retains
its integrity. The inclusion of glass fibres into gypsum
GYPSUM FLOOR SCREED plasterboards increases the cohesiveness of the material
within fires. Gypsum binders and gypsum plasters are
Gypsum interior floor screed, manufactured from a classified as Class A1 (no contribution to fire) if they
mixture of hemi-hydrate gypsum, limestone and less contain less than 1% of organic material.

Fig. 12.2 Preformed plaster coves RECYCLING GYPSUM PRODUCTS

A large proportion of gypsum for plasterboard (over
1 million tonnes per annum) is produced as a by-
product of the removal of sulphur dioxide from the
flue gasses of coal-fired electricity-generating stations.
A slurry of pulverised limestone absorbs the sulphur
dioxide, producing high-purity calcium sulphate.
However, the supply of this synthetic gypsum (known
as desulphogypsum DSG) is dependent upon the
continuing generation of electricity by coal-fired
stations as well as the sulphur content of the coal used.
Low-sulphur coal imported from Australia may reduce
the production of desulphogypsum.

Waste of plasterboard on site is high, ranging from
10–25% of the delivered material. Disposal in land-
fill sites is very limited, as gypsum, in association

PLASTER AND BOARD MATERIALS 391

with biodegradable materials, can produce toxic partition linings, suspended ceilings, fascias, soffits,
hydrogen sulphide. Gypsum products must therefore weatherboarding and fire protection to structural steel-
be deposited in biodegradable-free locations. Currently, work. External cladding boards may be finished with a
the industry maximum recycled gypsum content for sprayed or trowelled render to produce a seamless
plasterboard is 18%. The paper liners for plasterboard finish. (The thermal conductivities of calcium silicate
are made from 97% recycled paper and cardboard. boards are usually within the range 0.13–0.29 W/m K
One manufacturer will collect all of its own surplus depending upon their composition.)
gypsum board, ceiling tiles, coving and GRG from site
for recycling into new products. References

The publication PAS 109: 2008 gives the specifi- FURTHER READING
cation for the production of recycled gypsum from
waste plasterboard. British Geological Survey. 2006: Gypsum. London:
Office of the Deputy Prime Minister.
Lime plaster
British Gypsum. 2009: The white book. Loughborough:
Hydraulic lime plaster is suitable for interior appli- British Gypsum Ltd.
cation, particularly on earth structures and unfired clay
walls. It is usually applied in two or three coats – the British Gypsum. 2011: The fire book. Loughborough:
best-quality work requiring the three-coat system. In British Gypsum Ltd.
this case a 13 mm coat of coarse stuff containing 5 mm
sand (lime : sand, 1 : 2.5) is followed, when dry, with a Millar, W. and Bankart, G. 2009: Plastering plain
similar thickness of a 1 : 3 mix and a thin final coat of and decorative, 4th edn. Shaftesbury: Donhead
between 1 : 1 and 1 : 2 lime to sand. Other additions, Publishing.
including horsehair and cow dung, may be added to
improve the setting properties of the lime plaster. STANDARDS

Calcium silicate boards BS 476
Fire tests on building materials and structures:
Calcium silicate boards are manufactured from silica Part 4: 1970 Non-combustibility test for
with lime and/or cement, usually incorporating cellu- materials.
lose fibres or softwood pulp and mica or exfoliated Part 6: 1989 Methods of test for fire
vermiculite filler, to produce a range of densities. propagation for products.
The high-density material is laminated under steam Part 7: 1997 Method of test to determine the
and pressure, while the lower-density material is pro- classification of the surface
duced by rolling followed by curing in an autoclave. spread of flame of products.
Calcium silicate boards, like gypsum boards, are non-
combustible. The material is grey or off-white in colour, BS 5270
easily worked and nailed. Calcium silicate boards are Bonding agents for use with gypsum plasters and
durable, moisture-, chemical- and impact-resistant cement:
with dimensional stability and a good strength-to- Part 1: 1989 Specification for polyvinyl
weight ratio. They are available with a range of smooth acetate (PVAC) emulsion
or textured factory finishes for interior or exterior bonding agents for indoor use
use and also laminated to extruded polystyrene for with gypsum building plasters.
enhanced insulation properties. Standard thicknesses
range from 4.5–20 mm, although thicknesses up to BS 6100
100 mm are available in the vermiculite lightweight Building and civil engineering. Vocabulary:
boards used for fire protection giving up to 240 min- Part 9: 2007 Work with concrete and
utes’ resistance. The standard fire-resistance class is plaster.
A2-s1, d0. Typical applications include wall, roof and
BS 7364: 1990
Galvanized steel studs and channels for stud and
sheet partitions and linings using screw fixed
gypsum wallboards.

BS 8000
Workmanship on building sites:

392 PLASTER AND BOARD MATERIALS

Part 8: 1994 Code of practice for BS EN 13658
plasterboard partitions and dry Metal laths and beads. Definitions, requirements
linings. and test methods:
Part 1: 2005 Internal plastering.
BS 8212: 1995 Part 2: 2005 External rendering.
Code of practice for dry lining and partitioning
using gypsum plasterboard. BS EN 13815: 2006
Fibrous gypsum plaster casts. Definitions,
BS 8481: 2006 requirements and test methods.
Design, preparation and application of internal
gypsum, cement, cement and lime plastering BS EN ISO 13823: 2010
systems. Specification. Reaction to fire tests for building products.
Building products excluding floorings.
BS 9250: 2007
Code of practice for the design of airtightness of BS EN 13914
ceilings in pitched roofs. Design, preparation and application of external
rendering and internal plastering:
BS EN 520: 2004 pr Part 1: 2013 External rendering.
Gypsum plasterboards. Definitions, requirements pr Part 2: 2013 Design considerations and
and test methods. essential principles for internal
plastering.
BS EN 998
Specification for mortar for masonry: BS EN 13915: 2007
Part 1: 2010 Rendering and plastering Prefabricated gypsum plasterboard panels with a
mortar. cellular paperboard core.

BS EN ISO 1182: 2010 pr EN 13950: 2011
Reaction to fire tests for products. Non- Gypsum plasterboard thermal/acoustic insulation
combustibility test. composite panels. Definitions, requirements and
test methods.
BS EN ISO 1716: 2010
Reaction to fire tests for products. Determination pr EN 13963: 2011
of the gross heat of combustion. Jointing materials for gypsum plasterboards.
Definitions, requirements and test methods.
BS EN ISO 11925–2: 2010
Reaction to fire tests. Ignitability of products. pr EN 13964: 2014
Single flame source. Suspended ceilings. Requirements and test
methods.
BS EN 12859: 2011
Gypsum blocks. Definitions, requirements and pr EN 14190: 2011
test methods. Gypsum, plasterboard products from processing.
Definitions, requirements and test methods.
BS EN 12860: 2001
Gypsum based adhesives for gypsum blocks. BS EN 14195: 2005
Definitions. Metal framing components for gypsum
plasterboard systems. Definitions, requirements
BS EN 13055–1: 2002 and test methods.
Lightweight aggregates for concrete, mortar and
grout. BS EN 14209: 2005
Preformed plasterboard cornices. Definitions,
BS EN 13139: 2013 requirements and test methods.
Aggregates for mortar.
BS EN 14246: 2006
BS EN 13279 Gypsum elements for suspended ceilings.
Gypsum binders and gypsum plasters: Definitions, requirements and test methods.
Part 1: 2008 Definitions and requirements.
Part 2: 2014 Test methods. BS EN 14353: 2007
Metal beads and feature profiles for use with
BS EN 13501 gypsum plasterboards. Definitions, requirements
Fire classification of construction products and and test methods.
building elements:
Part 1: 2007 Classification using data from BS EN 14496: 2005
reaction to fire tests. Gypsum-based adhesives for thermal/acoustic
Part 2: 2007 Classification using data from insulation composite panels and plasterboards.
fire resistance tests.

PLASTER AND BOARD MATERIALS 393

BS EN 14566: 2008 Part 1: 2013 Requirements for factory
Mechanical fasteners for gypsum plasterboard premixed EPS dry plaster.
systems. Definitions, requirements and test
methods. Part 2: 2013 Processing of the factory
premixed EPS dry plaster.
PD CEN/TR 15123: 2005
Design, preparation and application of internal PD CEN/TR 16239: 2011
polymer plastering systems. Installation rules of fibrous gypsum plaster works.

BS EN 15254 NS/PAS 109: 2013
Extended application of results from fire- Specification for the production of reprocessed
resistance tests: gypsum from waste plasterboard.
Part 2: 2009 Non-loadbearing walls. Masonry
and gypsum blocks. BUILDING RESEARCH ESTABLISHMENT
Part 7: 2012 Non-loadbearing ceilings. Metal PUBLICATIONS
sandwich panels construction.
BRE Good building guides
BS EN 15283
Gypsum boards with fibrous reinforcement: BRE GBG 65: 2005
Part 1: 2008 Gypsum boards with mat Plastering and internal rendering.
reinforcement.
Part 2: 2008 Gypsum fibre boards. BRE GBG 70: 2007
Plasterboard; types and their applications (Parts 1,
BS EN 15318: 2007 2 and 3).
Design and application of gypsum blocks.
BRE Good repair guide
BS EN 15319: 2007
General principles of design of fibrous (gypsum) BRE GRG 18: 1998
plaster works. Replacing plasterwork.

BS EN 15824: 2009 ADVISORY ORGANISATION
Specifications for external renders and internal
plasters based on organic binders. Gypsum Products Development Association, PO Box
35084, London NW1 4XE (0207 935 8532).
BS EN 16025: 2013
Thermal and/or sound insulating products in
building construction. Bound EPS ballasting:

13

INSULATION MATERIALS

CONTENTS

Introduction 394 Sheep’s wool 400
Thermal and sound insulation Cellulose insulation 401
395 Recycled plastic 402
materials 396 Flax, hemp and coconut fibre 402
Forms of insulation materials 396 Wood fibre products 402
Inorganic insulation materials 396 Expanded polystyrene 403
Foamed concrete 397 Extruded polystyrene 404
Lightweight aggregate concrete 397 Expanded PVC 405
Gypsum plaster 397 Polyisocyanurate foam 405
Wood wool products 397 Polyurethane foam 406
Mineral wool 398 Urea-formaldehyde foam 406
Glass wool 399 Phenolic foam 406
Cellular or foamed glass blocks 399 Aluminium foil 406
Exfoliated vermiculite 399 Thermo-reflective insulation products 407
Expanded perlite 399 Panel systems 408
Calcium silicate 400 Vacuum insulation panels 408
Glass and multiple glazing 400 Gas-filled panels 408
Aerogel 400 References 408
Organic insulation materials 400
Cork products

Introduction

With the increasing emphasis on energy-conscious buildings. It is a UK government requirement that
design and the broader environmental impact of build- all new homes will be net zero carbon from 2016. To
ings, greater attention is being focused on the appro- achieve this, thermal insulation specifications need to
priate use of thermal and sound insulation materials support the Fabric Energy Efficiency Standards which
for both new-build and refurbishment work. The are the maximum space heating and cooling demands
UK government has set the target of reducing overall for zero carbon homes in relation to their house types.
greenhouse gas emissions from the 1990 baseline Even higher building fabric specifications are associated
by 80% by 2050, with an interim 50% cut by 2030. with the Passivhaus standards (Chapter 18, page 475).
Currently, 27% of UK carbon emissions are from The equivalent target date of net zero carbon for
domestic buildings and 17% from non-domestic new non-domestic buildings is 2019. The broad energy

INSULATION MATERIALS 395

conservation criteria within the Approved Documents increased by leakage at discontinuities within the
of the Building Regulations Part L – Conservation building fabric, particularly around unsealed openings.
of Fuel and Power (2013 edition) are outlined in Flanking sound is transmitted between rooms via the
Chapter 2 (page 44) and Chapter 7 (page 286), although adjoining elements rather than directly through the
there is some variation of requirements among the separating wall. The reduction in sound energy passing
countries of the UK. through a building element is expressed in decibels
(dB). The doubling of the mass of a building compo-
Thermal and sound insulation nent reduces the sound transmission by approximately
materials 5 dB; thus, sound-insulating materials are generally
heavy structural elements. However, the judicious use
To consider the relative efficiency of insulating of dissipative absorbers within walls can reduce the
materials, the thermal conductivities (␭ W/m K) are reliance for sound absorption on mass alone. Noise
quoted at the standard 10°C to allow direct compar- may be transmitted through services installations, so
isons. U-values would not illustrate direct compara- consideration should be given to the use of acoustic
bility owing to the varying thicknesses used and the sleeves and linings as appropriate.
wide variety of combinations of materials typically used
in construction. For dwellings, the Approved Documents of the
UK Building Regulations Part E (2010) ‘Resistance to
In considering acoustic control, distinction is made the Passage of Sound’ requires protection against sound
between the reduction of sound transmitted directly from adjacent buildings and within buildings including
through the building components and the attenu- internal walls and floors. The use of Robust Details in
ation of sound reflected by the surfaces within a housing can ensure adherence to the regulations and
particular enclosure. Furthermore, transmitted sound eliminate the requirement for pre-completion sound
is considered in terms of both impact and airborne testing to demonstrate compliance. The Building
sound. Impact sound is caused by direct impact onto Regulations list minimum criteria for the attenuation
the building fabric which then vibrates, transmitting the of airborne and impact sound.
sound through the structure; it is particularly signifi-
cant in the case of intermediate floors. Airborne sound- The absorption of sound at surfaces is related to the
waves, from the human voice and sound-generating porosity of the material. Generally, light materials
equipment, cause the building fabric to vibrate, thus with fibrous or open surfaces are good absorbers,
transmitting the sound. Airborne sound is particularly reducing ambient noise levels and reverberation times,
critical in relation to separating walls and is significantly whereas smooth, hard surfaces are highly reflective to
sound (Table 13.1). Sound absorption is measured
on a 0–1 scale, with 1 representing total absorption of
the sound.

Table 13.1 Typical sound absorption coefficients at 125, 500 and 2000 Hz for various building materials

Material Absorption coefficient

125 Hz 500 Hz 2000 Hz

Concrete 0.02 0.02 0.05
Brickwork 0.05 0.02 0.05
Plastered solid wall 0.03 0.02 0.04
Glass 6 mm 0.1 0.04 0.02
Timber boarding, 19 mm over air space against solid backing 0.3 0.1 0.1
Wood wool slabs, 25 mm, on solid backing, unplastered 0.1 0.4 0.6
Fibreboard, 12 mm on solid backing 0.05 0.15 0.3
Fibreboard, 12 mm over 25mm air space 0.3 0.3 0.3
Mineral wool, 25 mm with 5% perforated hardboard over 0.1 0.85 0.35
Expanded polystyrene board, 25 mm over 50 mm airspace 0.1 0.55 0.1
Flexible polyurethane foam, 50 mm on solid backing 0.25 0.85 0.9

396 INSULATION MATERIALS

Table 13.2 Typical thermal conductivity values for various building FORMS OF INSULATION MATERIALS
materials
Thermal and sound insulation materials may be
Material Thermal conductivity categorised variously according to their appropriate
(W/m K) uses in construction, their physical forms or their
material origin. Many insulating materials are available
Aerogel blanket 0.013 in different physical forms, each with their appropriate
Phenolic foam 0.018–0.031 use in building. Broadly, the key forms of materials may
Polyurethane foam (rigid) 0.019–0.023 be divided into:
Foil-faced polyisocyanurate foam 0.021
Polyisocyanurate foam 0.023–0.025 • structural insulation materials;
Sprayed polyurethane foam 0.024 • rigid and semi-rigid sheets and slabs;
Extruded polystyrene 0.028–0.036 • loose fill, blanket materials and applied finishes;
Expanded PVC 0.030 • aluminium foil;
Mineral wool 0.031–0.040 • vacuum- and gas-filled panels.
Glass wool 0.031–0.040
Expanded polystyrene 0.033–0.040 However, within this grouping it is clear that certain
Cellulose (recycled paper) 0.035–0.040 materials span two or three categories. Insulation
Sheep’s wool 0.037–0.039 materials are therefore categorised according to their
Rigid foamed glass 0.037–0.055 composition, with descriptions of their various forms,
Flax 0.038 typical uses in construction and, where appropriate, fire
Urea-formaldehyde foam 0.038 protection properties. Materials are initially divided
Wood fibre 0.038 into those of inorganic and organic origin respectively.
Hemp wool 0.040
Corkboard 0.042 The broad range of non-combustible insulating
Coconut fibre boards 0.045 materials is manufactured from ceramics and inorganic
Perlite board 0.045–0.050 minerals including natural rock, glass, calcium silicate
Fibre insulation board 0.050 and cements. Some organic products are manufactured
Straw bales 0.060 from natural cork or wood fibres but materials devel-
Exfoliated vermiculite 0.062 oped by the plastics industry predominate. In some
Hempcrete 0.060–0.090 cases these organic materials offer the higher thermal
Thatch 0.072 insulation properties but many are either inflammable
Wood wool slabs 0.077 or decompose within fire. Cellular plastics include
Medium-density fibreboard (MDF) 0.10 open- and closed-cell materials. Generally, the closed-
Foamed concrete (low density) 0.10 cell products are more rigid and have better thermal
Lightweight to dense concrete 0.10–1.7 insulation properties and resistance to moisture,
Compressed straw slabs 0.10 whereas the open-cell materials are more flexible and
Softwood 0.13 permeable. Aluminium foil is considered as a particular
Oriented strand board (OSB) 0.13 case, as its thermal insulation properties relate to the
Hardboard 0.13 transmission of radiant rather than conducted heat.
Particleboard/plywood 0.14 Typical thermal conductivity values are indicated in
Gypsum plasterboard 0.19 Table 13.2.
Bituminous roofing sheet 0.19
Cement bonded particleboard 0.23 Inorganic insulation materials
Unfired clay blocks 0.24
Calcium silicate boards 0.29 FOAMED CONCRETE
GRC – lightweight 0.21–0.5
GRC – standard density 0.5–1.0 The manufacture of foamed concrete is described in
Mastic asphalt 0.5 Chapter 3.
Calcium silicate brickwork 0.67–1.24
Clay brickwork 0.65–1.95 Foamed concrete with an air content in the range
Glass – sheet 1.05 30–80% is a fire- and frost-resistant material. Foamed

Notes:
Individual manufacturers’ products may differ from these typical figures.
Additional data is available in BS 5250: 2011, BS EN 12524: 2000 and
BS EN ISO 10456: 2007.

INSULATION MATERIALS 397

concrete can be easily placed without the need for com- WOOD WOOL PRODUCTS
paction but it does exhibit a higher drying shrinkage
than dense concrete. It is suitable for insulating under Wood wool products manufactured from wood
floors and on flat roofs where it may be laid to a fall fibres and cement (Chapter 4) are both fire and rot
of up to 1 in 100. (Thermal conductivity ranges from resistant. Wood wool boards, slabs (WW) and com-
0.10 W/m K at a density of 400 kg/m3 to 0.63 W/m K posite boards (WW-C) are described in BS EN 13168:
at a density of 1600 kg/m3.) 2012. With their combined load-bearing and insulating
properties, wood wool slabs are suitable as a roof
LIGHTWEIGHT AGGREGATE CONCRETE decking material, which may be exposed, painted or
plastered to the exposed lower face. Wood wool slabs
Lightweight concrete blocks and in situ concrete are offer good sound absorption properties due to their
discussed in Chapters 2 and 3, respectively. Lightweight open-textured surface, and this is largely unaffected by
concrete materials offer a range of insulating and the application of sprayed emulsion paint. Acoustic
load-bearing properties, starting from 0.10 W/m K at insulation for a pre-screeded 50 mm slab is typically
a crushing strength of 2.8 MPa. Resistance to airborne 30 dB. (The thermal conductivity of wood wool is
sound in masonry walls is closely related to the mass typically 0.077 W/m K.)
of the wall. However, any unfilled mortar joints which
create air paths will allow significant leakage of sound. MINERAL WOOL
In cavity walls, again mass is significant, but, in addi-
tion, to reduce sound transmissions the two leaves Mineral wool (MW) is manufactured from volcanic
should be physically isolated, with the exception of any rock (predominantly silica, with alumina and mag-
necessary wall ties, to comply with the Building nesium oxide), which is blended with coke and lime-
Regulations. stone and fused at 1500°C in a furnace. The melt runs
onto a series of rotating wheels which spin the droplets
GYPSUM PLASTER into fibres; they are then coated with resin binder and
water-repellent mineral oil. The fibres fall onto a
Plasterboard thermal linings will increase the thermal conveyor belt, where the loose mat is compressed to the
response in infrequently heated accommodation; the required thickness and density, then passed into an
effect may be enhanced with metallised polyester- oven where the binder is cured; finally, the product is
backed boards, which reduce radiant, as well as cut into rolls or slabs. New binders are bio-polymers
transmitted, heat loss. The addition of such linings rather than phenolic resins, thereby reducing the
for either new or upgrading existing buildings reduces embodied energy. Mineral wool is non-combustible,
the risk of thermal bridging at lintels, etc. (The water repellent and rot proof, and contains no CFCs or
thermal conductivity of gypsum plaster is typically HCFCs.
0.16 W/m K.)
Mineral wool is available in a range of forms
Sound transmission through lightweight walls can dependent upon its degree of compression during
be reduced by the use of two layers of differing thick- manufacture and its required use:
nesses of gypsum plasterboard (e.g. 12.5 and 19 mm),
as these resonate at different frequencies. The addition • loose for blown cavity insulation;
of an extra layer of plasterboard attached to existing • mats for insulating lofts, lightweight structures and
ceilings with resilient fixings can reduce sound trans-
mission from upper floors, particularly if an acoustic within timber framed construction;
quilt is also incorporated. • batts (slabs) for complete cavity fill of new masonry;
• semi-rigid slabs for partial cavity fill of new masonry;
Gypsum board thermal/acoustic composite and • rigid slabs for warm pitched roof and flat roof
sandwich panels are described in pr EN 13950: 2011.
Class 1 composites comprise gypsum board bonded to insulation;
expanded polystyrene, extruded polystyrene, rigid • rigid resin-bonded slabs for floor insulation;
polyurethane foam or phenolic foam. Class 2 com- • weather-resistant boards for inverted roofing
posites incorporate mineral wool.
systems;
• dense pre-painted boards for exterior cladding;
• ceiling tiles.

398 INSULATION MATERIALS

The mats and board materials may be faced with Flame to BS 476 Part 7 (1997) and Class 0 to Part 6
aluminium foil to enhance their thermal properties. (1989) on both their decorative and back surfaces. The
Roof slabs may be factory cut to falls or bitumen faced thermal conductivity of mineral wool suspended ceiling
for torch-on bitumen membrane roofing systems. tiles is typically within the range 0.052–0.057 W/m K.
Floor units are coated with paper when they are to be Sound attenuation of mineral wool ceiling tiles usually
directly screeded. A resilient floor can be constructed lies within the range 34–36 dB, but, depending upon
with floor units manufactured from mineral wool slabs, the openness of the tile surface, the sound absorp-
with the fibres orientated vertically rather than hori- tion coefficient may range from 0.1 for smooth tiles,
zontally, bonded directly to tongued and grooved through 0.5 for fissured finishes to 0.95 for open-cell
flooring-grade chipboard. tiles overlaid with 20 mm mineral wool.

The thermal conductivity of mineral wool products The standard BS EN 13162: 2012 covers both
for internal use varies typically between 0.031 and 0.039 mineral wool and glass wool boards, but in situ insula-
W/m K at 10°C, although products for external use have tion products are specified in BS EN 14064: 2010 and
higher conductivities ranging to 0.045 W/m K. products for industrial purposes are described in BS EN
14303: 2009. For in situ insulation, settlement should
Mineral wool may be used effectively to attenuate be limited to 1% in walls and not more than 10% in
transmitted sound. In lightweight construction, acous- loft applications.
tic absorbent quilts are effective in reducing transmitted
sound through separating walls when combined with GLASS WOOL
double plasterboard surfaces and a wide airspace, as
well as in traditional timber joist floors when combined Glass wool is made by the Crown process (Fig. 13.1),
with a resilient layer between joists and floor finish. which is similar to the process used for mineral wool.
Pelletised mineral wool may be used for pugging A thick stream of glass flows from a furnace into a
between floor joists to reduce sound transmission, and forehearth and by gravity into a rapidly rotating steel
is particularly appropriate for upgrading acoustic alloy dish, punctured by hundreds of fine holes around
insulation during refurbishment. its perimeter. The centrifugal force expels the filaments
which are further extended into fine fibres by a blast of
Mineral wool, due to its non-combustibility, is used hot air. The fibres are sprayed with a bonding agent and
for the manufacture of fire stops to prevent fire spread then sucked onto a conveyor to produce a mat of the
through voids and cavities, giving fire resistance ratings appropriate thickness. This is cured in an oven to set
of between 30 and 120 minutes. Mineral wool slabs give the bonding agent, then finally cut, trimmed and
typically between 60 and 240 minutes’ fire protection packaged.
to steel. Similar levels of protection may be achieved
with sprayed-on mineral wool, which may then be Glass wool is non-combustible, water repellent and
coated with a decorative finish. rot proof, contains no CFCs or HCFCs and is available
in a range of product forms:
Ceiling tiles for suspended ceilings manufactured
from mineral wool typically provide Class 1 Spread of

Fig. 13.1 Crown process for the manufacture of glass wool

INSULATION MATERIALS 399

• loose for blown cavity wall insulation; externally or within the cavity of external walls.
• rolls, either unfaced or laminated between kraft Externally, it may be rendered or tile hung and
internally finished with plasterboard or expanded metal
paper and polythene, for roofs, within timber frame and conventional plaster. (The thermal conductivity of
construction, internal walls and within floors; cellular glass is within the range 0.037–0.055 W/m K at
• semi-rigid batts with water-repellent silicone for 10°C, depending upon the grade.)
complete cavity fill of new masonry;
• rigid batts for partial cavity fill within new EXFOLIATED VERMICULITE
masonry;
• compression-resistant slabs for solid concrete or Exfoliated vermiculite (EV) is manufactured by heat-
beam and slab floors; ing the natural micaceous mineral. The material, con-
• a laminate of rigid glass wool and plasterboard for taining up to 90% air by volume, is used as a loose fill
dry linings; for loft insulation and within a cementitious spray
• PVC-coated rigid panels for exposed factory roof produces a hard fire-protection coating for exposed
linings. structural steelwork. Where thicknesses over 30 mm
are required, application should be in two coats. The
(The thermal conductivity of glass wool products product has a textured surface finish which may be
ranges typically between 0.031 and 0.040 W/m K at exposed internally or painted in external applications.
10°C.) Depending upon the thickness of application and the
A/V ratio (section factor) between exposed surface area
The sound- and fire-resistant properties of glass and steel volume (Chapter 5), up to 240 minutes’ fire
wool are similar to those of mineral wool. Glass wool protection may be obtained. Vermiculite is used for
sound-deadening quilts, which have overlaps to seal certain demountable fire stop seals where services
between adjacent units, are used to reduce impact penetrate through fire compartment walls. The stand-
sound in concrete and timber floating floors. Standard ards BS EN 14317 Parts 1 and 2 describe coated and
quilts are appropriate for use in lightweight partitions hydrophobic vermiculite as well as premixed vermic-
and over suspended ceilings. ulite with binders. (The thermal conductivity of
exfoliated vermiculite is 0.062 W/m K. Within light-
Resin-bonded glass wool treated with water repellent weight aggregate concrete a thermal conductivity of
is used to manufacture some ceiling tiles which meet typically 0.11 W/m K may be achieved.)
the Class 0 fire-spread requirements of the Building
Regulations (BS 476: Parts 6 and 7) and also offer
sound absorption to reduce reverberant noise levels.

CELLULAR OR FOAMED GLASS BLOCKS EXPANDED PERLITE

Cellular or foamed glass (CG) is manufactured from Expanded perlite is manufactured by heating natural
a mixture of crushed glass and fine carbon powder volcanic rock minerals. It is used for loose and bonded
which, upon heating to 1000°C, causes the carbon to in situ insulation for roofs, ceilings, walls and floors
oxidise, creating bubbles within the molten glass. as well as predominantly as preformed boards which
The glass is annealed, cooled and finally cut to size. may be fibre reinforced. Expanded perlite boards
The black material is durable, non-combustible, easily (EPB) are described in BS EN 13169: 2012 and the
worked and has a high compressive strength. It is water loose fill material in BS EN 14316 Parts 1 and 2. (The
resistant due to its closed-cell structure, impervious to thermal conductivity of expanded perlite boards is
water vapour and contains no CFCs. Cellular glass 0.05 W/m K.)
products are described in BS EN 13167: 2012.
CALCIUM SILICATE
Cellular glass slabs are appropriate for roof insu-
lation, including green roofs and roof-top car parks Calcium silicate (CS), which is described in Chapter 12,
owing to their high compressive strength. Tapered slabs has the advantage of good impact resistance and is
are available to create roof falls. The slabs are usually very durable. Various wallboards are manufactured
bonded in hot bitumen to concrete screeds, profile with calcium silicate boards laminated to extruded
metal decking or reinforced bitumen membrane on polystyrene or reinforced with fibres. The standard
timber roofing. Foamed glass is suitable for floor
insulation under the screed, and may be used internally,

400 INSULATION MATERIALS

BS EN 14306: 2009 specifies calcium silicate products. Organic insulation materials
(Calcium silicate typically has a thermal conductivity
of 0.29 W/m K.) The use of straw bales is described in Chapter 17 with
other recycled products.
GLASS AND MULTIPLE GLAZING
CORK PRODUCTS
The thermal and sound insulation effects of double and
triple glazing and the use of low-emissivity glass are Cork is harvested from the cork oak (Quercus suber L.)
described in Chapter 7. on a nine-year (or more) cycle and is therefore consid-
ered to be an environmentally friendly material (Fig.
AEROGEL 13.2). For conversion into boards, typically used for roof
insulation, cork granules are expanded, then formed
Aerogels are extremely lightweight, hydrophobic under heat and pressure into blocks using the natural
amorphous silica materials with densities as low as resin within the cork. The blocks are trimmed to
2 kg/m3 (␳air = 1.2 kg/m3). They are manufactured by standard thicknesses or to a taper to produce falls for
solvent evaporation from silica gel under reduced flat roofs (Fig. 13.3). For increased thermal insulation
pressure. Aerogels are highly porous with typically properties, the cork may be bonded to closed-cell
95–97% and even 99.8% air space, but significantly polyurethane or polyisocyanurate foam. In this case the
the pore size of 20 nm is so small that it is less than the laminate should be laid with the cork uppermost. Cork
mean free path of nitrogen and oxygen in the air. products are unaffected by the application of hot
This prevents the air particles from moving and bitumen in flat roofing systems. Insulation cork board
colliding with each other, which would normally give (ICB) is described in BS EN 13170: 2012. (The thermal
rise to gas phase heat conduction. With only 3–5% conductivity of corkboard is typically 0.042 W/m K but
solid material, heat conduction in the solid phase is very some denser products have higher thermal conductivity.)
limited. When used to fully fill the cavity in glazing
units, 0.5–4 mm aerogel granules prevent the move- SHEEP’S WOOL
ment of air, thus reducing heat transfer by convection
currents. Limited heat transfer can therefore only occur Sheep’s wool is a very efficient renewable resource
across the glazing unit by radiation. insulation material, with a low conductivity that
compares favourably to other fibrous insulants. It is
Light transmission through aerogel is approximately available in grey batts ranging in thickness from 50 and
80% per 10 mm thickness, giving a diffuse light and 75 to 100 mm thick. Wool is a hygroscopic material;
eliminating the transmission of ultraviolet light. that is, it reversibly absorbs and releases water vapour,
Airborne sound transmission is reduced, particularly and this effect is advantageous when it is used for
for lower frequencies of less than 500 Hz. The material thermal insulation. When the building temperature
is hydrophobic and therefore resistant to mould rises, wool releases its moisture causing a cooling effect
growth. in the fibre and thus a reduced flow of heat into the
building. In winter the absorption of moisture warms
Polycarbonate glazing units filled with aerogel are the material. This evolution of heat helps prevent
available as 10 and 16 mm panels, over a range of sizes interstitial condensation in construction cavities by
to fit profiled glass trough sections (Chapter 7) or as maintaining the temperature of the fibres above the
translucent roof lights or wall panels (e.g. 1220 ϫ 3660 dew point, and also effectively reduces the heat loss
mm). One proprietary cladding and roofing system from the building.
uses aluminium framing to support a sandwich panel
of fibreglass sheets separated by aerogel. The panels, Wool is safe to handle, only requiring gloves and a
1200 ϫ 3600 mm or 1500 ϫ 3000 mm (maxima), have dust mask as minimal protection. It causes no irritation
U-values of 0.28W/m2 K. (The thermal conductivity of except in the rare cases of people with a specific wool
aerogel blanket is typically 0.013 W/m K.) allergy. Wool batts, which contain 85% wool and 15%
polyester to maintain their form, can easily be cut with
Recently aerographite and graphene aerogel have a sharp knife or torn to size. Wool is potentially
become the lightest manufactured solid materials at susceptible to rodents which may use it as a nesting
densities of 0.18 and 0.16 kg/m3 respectively.

INSULATION MATERIALS 401

Fall 1:60 50 mm 100 mm 100 mm 100 mm
1m 5m

Polyurethane Cork
or polyisocyanurate foam

Fig. 13.3 Cork insulation to falls for flat roofs – additional
insulation dependent on the structure

Fig. 13.2 Production of cork. Photographs: Arthur Lyons material if it is accessible, but the batts are treated with
an insecticide to prevent moth or beetle attack and
with an inorganic fire retardant.

Wool batt insulation is suitable for ventilated loft
applications between joists or rafters and for timber-
frame construction. It should be installed with a
vapour-permeable breather membrane on the cold
side, and kept clear of any metal chimneys or flues.
Wool also acts as an effective acoustic insulating
material. (The thermal conductivity of wool batts is
0.039 W/m K.)

Sheep’s wool has also been used experimentally as
loose fill insulation for lofts, sloping ceilings, timber-
frame walls and timber floors. Natural wool from sheep
that have not been dipped is washed several times to
remove the natural oil lanolin, then opened out to
the required density. It is sprayed with borax as a fire
retardant and insect repellent. Supplied loose as hanks,
wool is only suitable for locations where it will not get
wet, which would cause it to sag, thus reducing its
thermal efficiency. Wool insulation is a renewable
source with low embodied energy, but it is currently
more expensive than the standard mineral wool
alternative. (The thermal conductivity of loose wool is
0.037 W/m K.)

CELLULOSE INSULATION

Cellulose insulation is manufactured from shredded
recycled paper and other organic waste. It is treated
with borax for flammability and smouldering resist-
ance; this also makes it unattractive to vermin, and
resistant to insects, fungus and dry rot. Unlike mineral
fibre and glass fibre insulation it does not cause skin
irritation during installation. Recycled cellulose has a
low embodied energy compared to mineral and glass
fibre insulation, and when removed from a building it
may be recycled again or disposed of safely without
creating toxic waste. (Treatment with the inorganic
salt, borax, ensures that cellulose insulation conforms

402 INSULATION MATERIALS

to BS 5803 Part 4: 1985 – Fire Test Class 1 and the equivalent glass fibre or mineral wool, has no loose
Smoulder Test Class B2.) fibres which may cause irritation. The material is
available in rolls of thicknesses from 100–200 mm and
Cellulose insulation may be used directly from bags has a thermal conductivity of 0.043 W/m K.
for internal floors and also lofts where the required
eaves ventilation gap must be maintained. For other FLAX, HEMP AND COCONUT FIBRE
cavities, including sloping roof voids, the material is dry
injected under pressure, completely filling all spaces to As the demand for sustainable insulating materials
prevent air circulation. In breathing walls, cellulose increases, products derived from renewable flax, hemp
insulation is filled inside a breathing membrane, and coconut fibres are becoming available. Flax
which allows the passage of water vapour through to insulation is suitable for ventilated or breathing con-
the outer leaf of the construction. Cellulose may be structions. The batts may be used in ceilings and walls,
damp-sprayed in between wall studs before the wall is and rolls in lofts, suspended floors and walls. Flax
closed. Cellulose is a hygroscopic material, which under is treated with borax for fire and insect resistance
conditions of high humidity absorbs water vapour and and bonded with potato starch, giving a moisture-
then releases it again under dry conditions. Cellulose absorbing, non-toxic product with good thermal and
is an effective absorber of airborne sound. acoustic insulation properties. (The thermal conduct-
ivity of flax is 0.038 W/m K.)
Loose-fill cellulose insulation (LFCI) is detailed
in the standards BS EN 15101 Parts 1 and 2: 2013. Chopped hemp fibres, treated with borax for fire
Classification with respect to settlement, resistance to resistance, are used to produce insulation batts, and also
mould and fire (BS EN 13501–1: 2007, BS EN 13823: as loose fill for floors and roofs. Hemp is also blended
2010 and BS EN ISO 11925–2: 2010) is required. (The with either wood fibres or waste cotton and 15%
thermal conductivity of cellulose insulation is 0.035 polyester fibres to form insulation batts. Hemp, a very
W/m K in horizontal applications and 0.038–0.040 tough material, is used in the manufacture of certain
W/m K in walls.) particleboards in Germany and generally for paper
production. Hempcrete is described in Chapter 3. (The
RECYCLED PLASTIC thermal conductivities of hemp insulation products
are in the range 0.038–0.040 W/m K.)
Loft insulation material is manufactured from re-
cycled plastic bottles which are converted into a non- Coconut fibre thermal and acoustic insulation
woven, clean material (Fig. 13.4). The product contains boards have the advantage of natural rot resistance.
approximately 85–90% of recycled material, and unlike They are available in a range of thicknesses from
10–25 mm, and typical uses include ceiling and floor
insulation including under-screed applications. (The
thermal conductivity of coconut fibre is 0.045 W/m K.
The sound reduction for a typical 18 mm under-screed
application is 26 dB.)

Fig. 13.4 Recycled plastic insulation WOOD FIBRE PRODUCTS

Wood fibre (WF) insulation to BS EN 13171: 2012 is
produced to a range of forms including mat, batt, felt,
roll and board. The manufacture of softboard, which
is a low-density wood fibre building board, is described
in Chapter 4. Standard grades of insulating board
should only be used in situations where they are not in
contact with moisture, or at risk from the effects of
condensation. Insulating board is used for wall linings
and may be backed with aluminium foil for increased
thermal insulation.

Insulating board may be impregnated with
inorganic fire retardants to give a Class 1 Surface Spread

INSULATION MATERIALS 403

of Flame to BS 476 Part 7 or finished with plaster- acids and alkalis but is readily dissolved by most organic
board to give a smooth Class 0 fire rated surface. The solvents. It is rot and vermin proof. Expanded poly-
Euroclass fire performance rating under the conditions styrene is described in BS EN 13163: 2012.
specified in BS EN 13986: 2004 for 9 mm untreated
high-density medium board of 600 kg/m3 is Class Polystyrene beads
D-s2, d0 for non-floor use. For untreated low-density
medium board of 400 kg/m3 the equivalent rating is Expanded polystyrene beads are used as loose fill for
Class E, pass for non-floor use, and for 9 mm untreated cavity insulation. To prevent subsequent slippage and
softboard of 250 kg/m3 the rating is Class E, pass for escape through voids, one system bonds the polystyrene
non-floor use. Manufacturers are required to specify beads by spraying them with atomised PVA adhesive
fire resistance to BS EN 13501–1: 2007. during the injection process, although other processes
leave the material loose. Walls up to 12 m in height can
Exposed insulating board has good sound-absorbing be insulated by this type of system. Polystyrene bead
properties due to its surface characteristics. Standard insulation should not be used where electrical wiring
12 mm lining softboard has a noise-reduction coeffi- is present in the cavity, as the polystyrene gradually
cient of 0.42, although this is increased to 0.60 for the leaches the plasticiser out from plastic cables, causing
24 mm board. their embrittlement, which could lead to problems later
if the cables are subsequently moved. Polystyrene bead
Bitumen-impregnated insulating board, with its aggregate cement is used to form an insulating sand-
enhanced water-resistant properties, is used as a wich core in concrete cladding panel systems.
thermal insulation layer on concrete floors. The
concrete floor slab is overlaid with polythene, followed Expanded polystyrene boards
by bitumen-impregnated insulation board and the
required floor finish such as particleboard. In the Expanded polystyrene rigid lightweight boards are
upgrading of existing suspended timber floors, a used for thermal insulation and four standard grades
loosely laid layer of bitumen-impregnated insulating are available (Table 13.3). The standard material is
board under a new floor finish can typically reduce classified as Euroclass F in relation to fire, but certain
both impact and airborne sound transmission by 10 dB. flame-retardant modified boards are classified as
Bitumen-impregnated insulating board is frequently Euroclass E. (Grades range from A1 and A2 through
used in flat-roofing systems as a heat protective layer to F.) Non-load-bearing expanded polystyrene for
to polyurethane, polystyrene or phenolic foams prior impact sound insulation properties is designated type
to the application of the hot bitumen waterproof EPS SD to BS EN 13163: 2012.
membrane. It is also used for sarking in pitched roofs.
(The thermal conductivity of insulating board is The boards, which are manufactured by fusing
typically 0.050 W/m K.) together pre-foamed beads under heat and pressure,
can easily be cut, sawn or melted with a hot wire.
Rigid and semi-rigid wood fibre insulation panels Polystyrene boards provide thermal insulation for
with thicknesses ranging from 20–240 mm are used for walls, roofs and floors. In addition, polystyrene may be
wall, roof and intermediate floor applications. Boards cast into reinforced concrete, from which it is easily
are available with either a butt or tongue and groove removed to create voids for fixings.
edge profile. Fire classification to BS EN 13501–1: 2007
is usually Class E. Thermal conductivity is typically In cavity wall insulation, a 50 mm cavity may be
within the range 0.036–0.042 W/m K. The equivalent retained to prevent the risk of water penetration, with
blown material may be used to fill void spaces giving a proprietary wall ties fixing the boards against the inner
thermal conductivity of 0.038–0.043 W/m K, depend- leaf. Alternatively, with a fully filled cavity system, the
ing upon the density of the fill. boards may be slightly moulded on the outer surface
to shed any water back onto the inside of the external
EXPANDED POLYSTYRENE masonry leaf. Interlocking joints prevent cold bridg-
ing, air leakage and water penetration at the board
Expanded polystyrene (EPS) is a combustible material, joints. In upgrading existing walls (Fig. 13.5), external
which, in fire, produces large quantities of noxious expanded polystyrene insulation should be protected
black smoke, although Type A, with a flame-retardant by suitably supported rendering, tile hanging or brick
additive, is not easily ignitable. Expanded polystyrene, slips. Clay, concrete or acrylic brick slips may be
a closed-cell product, is unaffected by water, dilute

404 INSULATION MATERIALS

Table 13.3 Standard grades of expanded polystyrene (BS 3837–1: 2004 and BS EN 13163: 2012)

Grade Type Description Typical density Thermal conductivity
BS 3837 BS EN 13163 (kg/m3) (W/m K)

SD EPS 70 Standard duty 15 0.038
0.036
HD EPS 100 High duty 20 0.035
0.034
EHD EPS 150 Extra-high duty 25

UHD EPS 200 Ultra-high duty 30

Notes:
– BS EN 13163: 2012 lists the range of types from EPS 30 to EPS 500 (Compressive strengths from 30 to 500 kPa respectively).
– BS EN 13163: 2012 refers to four types of expanded polystyrene:

EPS – load-bearing applications
EPS S – non-load-bearing applications
EPS SD – non-load-bearing applications with acoustic properties
EPS T – floating floor applications.

mounted on steel panels or mesh and may be pointed Expanded polystyrene incorporating graphite is grey in
or mortarless. Weatherproof rendering should tolerate colour and has enhanced thermal insulation properties,
thermal and moisture movement and be frost resistant as it absorbs infrared radiation and reflects heat. (The
to minimise maintenance. For internal wall insulation, thermal conductivity of expanded polystyrene is in the
expanded polystyrene may be used in conjunction with range 0.033–0.040 W/m K depending upon the grade.
12.5 mm plasterboard either separately or as a laminate. The graphite product has a thermal conductivity of
Expanded polystyrene (Type EPS T) is used to give 0.033 W/m K.)
thermal insulation in ground floors. It may be laid
below or above the oversite slab; in the latter case, it EXTRUDED POLYSTYRENE
may be screeded or finished with chipboard. Composite
floor panels manufactured from expanded polystyrene Extruded polystyrene (XPS) is manufactured by the
and oriented strand board are suitable for beam and extrusion of a heated mixture of polystyrene and
block floors, while proprietary systems offer thermal expansion agent through a die. The continuous ribbon
insulation to prestressed concrete beam and reinforced of expanded material is cooled and trimmed. It is
concrete screed floors. Expanded polystyrene boards slightly denser and therefore slightly stronger in com-
reduce impact and airborne sound transmission pression than expanded polystyrene but has a lower
through intermediate floors. thermal conductivity. It has a closed-cell structure with
very low water-absorption and vapour-transmission
Expanded polystyrene is suitable for thermal properties. It is produced either with or without a
insulation in flat and pitched roofs. For flat roofs it polystyrene skin. Extruded polystyrene is described
may be cut to falls. Where hot bitumen products are in BS EN 13164: 2012. It is available with densities
to be applied, the expanded polystyrene boards must ranging from 20–40 kg/m3. Extruded polystyrene is
be protected by an appropriate layer of bitumen- widely used for cavity wall and pitched roof insulation.
impregnated fibreboard, perlite board or corkboard. In Because of its high resistance to water absorption,
metal deck applications the insulating layer may be extruded polystyrene may be used for floor insulation
above or below the purlins, whereas in traditional below the concrete slab and on inverted roofs where
pitched roofs expanded polystyrene panels are norm- its resistance to mechanical damage from foot traffic is
ally installed over the rafters. Expanded polystyrene, advantageous. Extruded polystyrene is also available
although a closed-cell material, acts as a sound absorber, laminated to tongued and grooved moisture-resistant
provided that it is installed with an air gap between it flooring grade particleboard for direct application to
and the backing surface. It particularly absorbs sound concrete floor slabs, and laminated to plasterboard as
at low frequencies and may be used in floors and a wallboard. (The thermal conductivity of extruded
ceilings. It is, however, less effective than the open- polystyrene is typically 0.033–0.035 W/m K.)
cell materials, such as flexible polyurethane foam.

INSULATION MATERIALS 405

Fig. 13.5 Retrofit external polystyrene insulation

EXPANDED PVC floor insulation. PIR is combustible (BS 476 Part 4)
with a Class 1 Surface Spread of Flame (BS 476 Part 7)
Plasticised PVC open-, partially open- and closed-cell but is more fire resistant than polyurethane foam
foams are manufactured as flexible or rigid products and can be treated to achieve Class 0 rating. Polyiso-
within the density range of 24–72 kg/m3. The rigid cyanurate foam boards have a fire classification of
closed-cell products provide low water permeability Class F, but the Building Regulations permit their use
and are self-extinguishing in fire. Expanded PVC in wall cavities within masonry leaves of at least 75 mm
boards are used in sandwich panels and for wall linings. thickness (BS 4841: 2006). Polyisocyanurate tends to be
The low-density open-cell material has particularly rather friable and brittle. Certain proprietary systems
good acoustic absorbency and may be used to reduce for insulated cavity closers use PVC-U-coated poly-
sound transmission through unbridged cavities and isocyanurate insulation. Such systems offer a damp-
floating floors. (The thermal conductivity of expanded proof barrier and can assist in the elimination of cold
PVC is typically 0.030 W/m K.) bridging, which sometimes causes condensation and
mould growth around door and window openings.
POLYISOCYANURATE FOAM In situ formed polyisocyanurate foam, described in
BS EN 14315: 2013, is delivered as a two-component
Polyisocyanurate foam (PIR) is usually blown with sprayed mix which subsequently expands to fill the
pentane. It is used as a roof insulation material since it void space. (The thermal conductivity of polyiso-
is more heat resistant than other organic insulation cyanurate foam is usually in the range 0.023–0.025
foams, which cannot be directly hot-bitumen bonded. W/m K.)
Polyisocyanurate is also appropriate for use in wall and

406 INSULATION MATERIALS

POLYURETHANE FOAM W/m K at a nominal density of 32 kg/m3. Flexible
polyurethane foam typically has a thermal conductivity
Rigid polyurethane (PUR) is a closed-cell foam manu- of 0.048 W/m K.)
factured using pentane or carbon dioxide. Pentane
remains trapped within the closed cells, enhancing the UREA-FORMALDEHYDE FOAM
thermal performance, but carbon dioxide diffuses
out. Certain polyurethanes are modified with polyiso- Urea-formaldehyde foam (UF) was used extensively in
cyanurates. Polyurethane foam products are defined in the 1980s for cavity wall insulation, but it can shrink
BS EN 13165: 2012. after installation, creating fissures which link the outer
and inner leaves. Occasionally, in conditions of high
Rigid polyurethane is a combustible material pro- exposure, this had led to rain water penetration. After
ducing copious noxious fumes and smoke in fire, installation the urea-formaldehyde foam emits form-
although a flame-resistant material is available. Poly- aldehyde fumes, which have in certain cases entered
urethane boards have a fire classification of Class F, buildings, causing occupants to suffer from eye and
but the Building Regulations permit their use in nose irritation. The problem normally arises only if
wall cavities within masonry leaves of at least 75 mm the inner leaf is permeable and a cavity greater than
thickness (BS 4841: 2006). Polyurethane is used to 100 mm is being filled. Recent advances claim to
enhance the thermal insulation properties of concrete have reduced formaldehyde emissions but all installa-
blocks either by filling the void spaces in hollow blocks tions must be undertaken to the stringent British
or by direct bonding onto the cavity face. Roofboards, Standard BS 5618: 1985. The Health & Safety Executive
in certain systems pre-bonded to bitumen roofing advises against the use of urea formaldehyde where
sheet, are suitable for mastic asphalt and reinforced the inner leaf of the cavity wall is porous or has
bitumen membrane roofing systems. Owing to the unsealed connections with the interior. (The thermal
temperature stability of polyurethane no additional conductivity of urea-formaldehyde foam is typically
protection from the effects of hot bitumen application 0.038 W/m K.)
is required; the durability of the material also makes
it suitable for use in inverted roofs. Laminates with PHENOLIC FOAM
foil or kraft paper are available. Factory-manufactured
double-layer profiled-metal sheeting units are fre- Phenolic foams (PF), which have very low thermal
quently filled with rigid polyurethane foam due to conductivities, are used as alternatives to rigid
its good adhesive and thermal insulation proper- polyurethane and polyisocyanurate foams, where a
ties. Polyurethane laminated to plasterboard is used self-extinguishing, low smoke emission material is
as a wallboard. When injected as a premixed two- required. Phenolic foams are produced with densities
component system into cavity walls polyurethane in the range 35–200 kg/m3. The closed-cell material
adheres well to the masonry, foaming and expanding is usually expanded with pentane. Phenolic foam is
in situ to completely fill the void space (BS EN 14315: described in BS EN 13166: 2012. Wallboard lamin-
2013). It has been used in situations where the ates with plasterboard offer good thermal insulation
cavity ties have suffered serious corrosion, and where properties due to the very low thermal conductivity
additional bonding between the two leaves of masonry of phenolic foam, compared to polyurethane or
is required, but it is not now widely used as a cavity extruded polystyrene. Phenolic foams are stable up
insulation material. However, two-component poly- to a continuous temperature of 120°C. (The thermal
urethane foam spray is effective at closing gaps around conductivity of phenolic foam in the density range
service voids, eliminating cold bridges, under-tile 35–60 kg/m3 is typically 0.021 W/m K, although
insulation and for filling inaccessible locations. the open-cell material has a thermal conductivity of
0.031 W/m K.)
Flexible polyurethane foam is an open-cell material
offering good noise absorption properties. It is Aluminium foil
therefore used in unbridged timber frame partitions,
floating floors and duct linings to reduce noise trans- Aluminium foil is frequently used as an insulation
mission. Polyurethane foams are resistant to fungal material in conjunction with organic foam or insulating
growth, aqueous solutions and oils, but not to organic
solvents. (The thermal conductivity of rigid poly-
urethane foam is usually in the range 0.019–0.023

INSULATION MATERIALS 407

gypsum products. It acts by a combination of two and radiation (Fig. 13.6). A range of these thermo-
physical effects. First, it reflects back incident heat due reflective insulation products is manufactured using
to its highly reflecting surface. Second, owing to its low different combinations of thin plastic foam, plastic
emissivity, the re-radiation of any heat that is absorbed bubble sheet, and non-woven fibrous wadding with
is reduced. Thin aluminium reflective foil insulation plain and reinforced aluminium foil. For example, the
can be inserted between studs, joists or rafters, leaving combination of a nine-layer and 19-layer of thermo-
a 25 mm air gap on either side. In addition to insulation reflective insulation within standard timber stud-
it acts as an air infiltration and vapour barrier. ding produces a typical wall U-value of 0.22 W/m2 K.
The similar combination in conjunction with 25 mm
THERMO-REFLECTIVE INSULATION insulated plasterboard gives a typical roof U-value of
PRODUCTS 0.18 W/m2 K. The standard BS EN 16012: 2012 des-
cribes four types of product ranging from aluminium-
Proprietary quilt systems incorporating multi-layers of faced rigid foam to flexible multi-layer bubble-foil
aluminium foil, fibrous materials and cellular plastics systems. (The thermal conductivity of foil-faced foam
act as insulation by reducing conduction, convection is typically 0.020 W/m K.)

Fig. 13.6 Multi-layer aluminium foil insulation system

408 INSULATION MATERIALS

Panel systems Robust Details. 2013: Robust details handbook, 3rd edn.
Milton Keynes: Robust Details Ltd.
Panel systems based on the insulating effect of vacuum
or inert gas fill are under development, but not yet TRADA. 2008: England and Wales Building Regulations
commercially viable. Part E – Resistance to the passage of sound. High
Wycombe: TRADA Technology Ltd.
VACUUM INSULATION PANELS
Zero Carbon Hub. 2012: Fabric energy efficiency for
Vacuum insulation panels (VIPs) are evacuated Part L 2013.Worked examples and fabric specifi-
materials such as polyurethane foam or porous silica cations. Milton Keynes: NHBC.
powder, held within an aluminium-based multi-
layered envelope. Desiccants are usually incorporated Zero Carbon Hub. 2012: Fabric energy efficiency for
to maintain the vacuum. Care is required during Part L 2013. Classification methodology for different
transportation and installation to avoid damage to dwelling types. Milton Keynes: NHBC.
the vacuum.
STANDARDS
GAS-FILLED PANELS
BS 476
Gas-filled panels are similar to vacuum insulation Fire tests on building materials and structures:
panels but are filled with argon, krypton or xenon. The Part 4: 1970 Non-combustibility test for
envelope therefore does not need to resist atmospheric materials.
pressure, but the insulating effect is less than with a Part 6: 1989 Method of test for fire
vacuum. The incorporation of low-emissivity reflective propagation of products.
layers reduces heat transfer by radiation. Part 7: 1997 Method of test to determine the
classification of the surface
References spread of flame of products.

FURTHER READING BS ISO 633: 2007
Cork. Vocabulary.
Anderson, J. and Allbury, K. 2011: Environmental
impact of insulation. Garston: IHS BRE Press. BS ISO 2219: 2010
Thermal insulation products for building. Factory
Bynum, R. and Rubino, D. 2000: Insulation handbook. made products of expanded cork (ICB).
Maidenhead: McGraw. Specification.

Colwell, S. and Baker, T. 2013: Fire performance of BS 3379: 2005
external thermal insulation of walls of multi-storey Combustion modified flexible polyurethane
buildings. Garston: IHS BRE Press. cellular materials for loadbearing applications.
Specification.
Communities and Local Government. 2007: Accredited
construction details. Wetherby: Communities and BS 3533: 1981
Local Government Publications. Glossary of thermal insulation terms.

Doran, D. and Anderson, J. 2011: Environmental impact BS 3837
of vertical cladding. Garston: IHS BRE Press. Expanded polystyrene boards:
Part 1: 2004 Boards and blocks manu-
Pearson C. 2009: The complete guide to external wall factured from expandable
insulation. York: Wellgarth Publishing. beads.

Peters, R.J., Smith, B.J. and Hollins, M. 2011: Acoustics BS 4023: 1975
and noise control. Harlow: Prentice Hall. Flexible cellular PVC sheeting.

Pfundstein, M., Gellert, R., Spitzner, M. and Rudolphi, BS 4841
A. 2008: Insulating materials. Principles materials Rigid polyisocyanurate (PIR) and polyurethane
and applications. Basel: Birkhäuser. (PUR) for building end-use applications:
Part 1: 2006 Specification for laminated
insulation boards with auto-
adhesively or separately bonded
facings.
Part 2: 2006 Specification for laminated
boards for use as thermal

INSULATION MATERIALS 409

insulation for internal wall BS 5803
linings and ceilings. Thermal insulation for use in pitched roof spaces
Part 3: 2006 Specification for laminated in dwellings:
boards for use as roofboard Part 2: 1985 Specification for man-made
thermal insulation under built mineral fibre thermal insulation
up bituminous roofing in pelleted or granular form for
membranes. application by blowing.
Part 4: 2006 Specification for laminated Part 3: 1985 Specification for cellulose fibre
boards for use as roofboard thermal insulation for
thermal insulation under non- application by blowing.
bituminous single-ply roofing Part 4: 1985 Methods for determining
membranes. flammability and resistance to
Part 5: 2006 Specification for laminated smouldering.
boards for use as thermal Part 5: 1985 Specifications for installations of
insulation boards for pitched man-made mineral fibre and
roofs. cellulose fibre insulation.
Part 6: 2006 Specification for laminated
boards for use as thermal BS 5821
insulation for floors. Methods for rating the sound insulation in
BS 5241 buildings and of building elements:
Rigid polyurethane (PUR) and polyisocyanurate Part 3: 1984 Airborne sound insulation of
(PIR) foam when dispensed or sprayed on a façade elements and façades.
construction site:
Part 1: 1994 Specification for sprayed foam BS 6203: 2003
thermal insulation applied Guide to the fire characteristics and fire
externally. performance of expanded polystyrene materials
Part 2: 1991 Specification for dispensed foam (EPS and XPS) used in building applications.
for thermal insulation or
buoyancy applications. BS 7021: 1989
BS 5250: 2011 Code of practice for thermal insulation of roofs
Code of practice for control of condensation in externally by means of sprayed rigid polyurethane
buildings. (PUR) or polyisocyanurate (PIR) foam.
BS 5422: 2009
Method for specifying thermal insulating BS 7456: 1991
materials for pipes, tanks, vessels ductwork and Code of practice for stabilization and thermal
equipment. insulation of cavity walls by filling with
BS 5608: 1993 polyurethane (PUR) foam systems.
Specification for preformed rigid polyurethane
(PUR) and polyisocyanurate (PIR) foams for BS 7457: 1994
thermal insulation of pipework and Specification for polyurethane (PUR) foam
equipment. systems suitable for stabilization and thermal
BS 5617: 1985 insulation of cavity walls with masonry or
Specification for urea-formaldehyde (UF) foam concrete inner and outer leaves.
systems suitable for thermal insulation of cavity
walls with masonry or concrete inner and outer BS 8233: 2014
leaves. Guidance on sound insulation and noise
BS 5618: 1985 reduction for buildings.
Code of practice for thermal insulation of cavity
walls by filling with urea-formaldehyde (UF) foam BS ISO 12575–1: 2012
systems. Thermal insulation. Exterior insulating systems
for foundations. Material specification.

BS ISO 16346: 2013
Energy performance of buildings. Assessment of
overall energy performance.

BS ISO 16818: 2008
Building environment design. Energy efficiency.
Terminology.

410 INSULATION MATERIALS

BS EN ISO 717 Part 1: 2000 Airborne sound insulation
Acoustics. Rating of sound insulation in buildings between rooms.
and of building elements:
Part 1: 1997 Airborne sound insulation. Part 2: 2000 Impact sound insulation
Part 2: 1997 Impact sound insulation. between rooms.

BS EN ISO 5999: 2007 Part 3: 2000 Airborne sound insulation
Flexible cellular polymeric materials. Polyurethane against outdoor sound.
foam for load-bearing applications excluding
carpet underlay. Specification. Part 4: 2000 Transmission of indoor sound
to the outside.
BS EN ISO 6946: 2007
Building components and building elements. Part 5: 2009 Sound levels due to the service
Thermal resistance and thermal transmittance. equipment.
Calculation method.
Part 6: 2003 Sound absorption in enclosed
BS EN ISO 7345: 1996 spaces.
Thermal Insulation. Physical quantities and
definitions. BS EN 12524: 2000
Building materials and products. Hygrothermal
BS EN ISO 8990: 1996 properties. Tabulated design values.
Thermal insulation. Determination of steady-state
thermal transmission properties. BS EN ISO 12567
Thermal performance of windows and doors:
BS EN ISO 9229: 2007 Part 1: 2010 Complete windows and doors.
Thermal insulation. Vocabulary. Part 2: 2005 Roof windows and other
projecting windows.
BS EN ISO 10077
Thermal performance of windows, doors and BS EN ISO 12631: 2012
shutters. Calculation of transmittance: Thermal performance of curtain walling.
Part 1: 2006 General.
Part 2: 2012 Numerical method for frames. BS EN ISO 12655: 2013
Energy performance of buildings. Presentation of
BS EN ISO 10456: 2007 measured energy use of buildings.
Building materials and products. Hygrothermal
properties. Tabulated design values. BS EN 12758: 2011
Glass in building. Glazing and airborne sound
BS EN ISO 10848 insulation.
Acoustics. Laboratory measurement of the flank-
ing transmission of airborne and impact sound: BS EN ISO 12999–1: 2014
Part 1: 2006 Frame document. Acoustics. Determination and application of
Part 2: 2006 Application to light elements. measurement uncertainties in building acoustics.
Junction small influence. Sound insulation.
Part 3: 2006 Application to light elements.
Junction substantial influence. BS EN 13162: 2012
Part 4: 2010 Applications to junctions with Thermal insulation products for building. Factory
at least one heavy element. made mineral wool (MW) products. Specification.

BS EN ISO 11654: 1997 BS EN 13163: 2012
Acoustics. Sound absorbers for use in buildings. Thermal insulation products for building.
Factory made products of expanded polystyrene
BS EN ISO 11925–2: 2010 (EPS). Specification.
Reaction to fire tests. Ignitability of products
subjected to direct impingement of flame. Single- BS EN 13164: 2012
flame source test. Thermal insulation products for building.
Factory made products of extruded polystyrene
BS EN ISO 12241: 2008 foam (XPS). Specification.
Thermal insulation for building equipment and
industrial installations. Calculation rules. BS EN 13165: 2012
Thermal insulation products for building.
BS EN 12354 Factory made rigid polyurethane foam (PUR)
Building acoustics. Estimation of acoustic products. Specification.
performance of buildings from the performance
of elements: BS EN 13166: 2012
Thermal insulation products for building.
Factory made products of phenolic foam (PF).
Specification.

INSULATION MATERIALS 411

BS EN 13167: 2012 BS EN 13496: 2013
Thermal insulation products for building. Thermal insulation products for building
Factory made cellular glass (CG) products. applications. Determination of the mechanical
Specification. properties of glass fibre meshes as reinforcement
for external thermal insulation composite systems
BS EN 13168: 2012 (ETICS).
Thermal insulation products for building.
Factory made wood wool (WW) products. BS EN 13497: 2002
Specification. Thermal insulation products for building
applications. External thermal insulation.
BS EN 13169: 2012 Resistance to impact.
Thermal insulation products for building.
Factory made products of expanded perlite (EPB). BS EN 13498: 2002
Specification. Thermal insulation products for building
applications. External thermal insulation.
BS EN 13170: 2012 Resistance to penetration.
Thermal insulation products for building.
Factory made products of expanded cork (ICB). BS EN 13499: 2003
Specification. Thermal insulation products for building
applications. External thermal insulation
BS EN 13171: 2012 composite systems (ETICS) based on polystyrene.
Thermal insulation products for building. Factory Specification.
made wood fibre (WF) products. Specification.
BS EN 13501
BS EN 13172: 2012 Fire classification of construction products and
Thermal insulating products. Evaluation of building elements:
conformity. Part 1: 2007 Classification using test data
from reaction to fire tests.
BS EN ISO 13370: 2007 Part 2: 2007 Classification using data from
Thermal performance of buildings. Heat transfer fire resistance tests.
via the ground. Calculation methods.
BS EN ISO 13788: 2012
BS EN 13467: 2001 Hygrothermal performance of building
Thermal insulation for building equipment and components and building elements. Calculation
industrial installations. Preformed pipe insulation. methods.

BS EN 13469: 2012 BS EN ISO 13789: 2007
Thermal insulation for building equipment and Thermal performance of buildings. Transmission
industrial installations. Preformed pipe insulation. and ventilation heat transfer coefficients.
Water vapour transmission properties. Calculation method.

BS EN 13470: 2012 BS EN ISO 13790: 2008
Thermal insulation for building equipment and Thermal performance of buildings. Calculation of
industrial installations. Preformed pipe insulation. energy use for space heating and cooling.
Apparent density.
BS EN ISO 13791: 2012
BS EN 13471: 2001 Thermal performance of buildings. Calculation of
Thermal insulation for building equipment and internal temperatures of a room in summer.
industrial installations. Coefficient of thermal General criteria and validation procedures.
expansion.
BS EN ISO 13792: 2012
BS EN 13472: 2012 Thermal performance of buildings. Calculation of
Thermal insulation for building equipment and internal temperatures. Simplified methods.
industrial installations. Preformed pipe insulation.
Water absorption. BS EN 13823: 2010
Reaction to fire tests for building products.
BS EN 13494: 2002 Building products excluding floorings exposed to
Thermal insulation products for building the thermal attack by a single burning item.
applications. Bond strength to thermal insulation
material. pr EN 13950: 2011
Gypsum plasterboard thermal/acoustic insulation
BS EN 13495: 2002 composite panels.
Thermal insulation products for building
applications. Pull off resistance.

412 INSULATION MATERIALS

BS EN 13986: 2004 BS EN 14315
Wood-based panels for use in construction. Thermal insulation products for buildings. In-situ
Characteristics, evaluation of conformity and formed sprayed rigid polyurethane (PUR) and
marking. polyisocyanurate (PIR) products:
Part 1: 2013 Specification for the rigid foam
BS EN 14063 before installation.
Thermal insulation products for building. In-situ Part 2: 2013 Specification for the installed
formed expanded clay lightweight aggregate insulation products.
products:
Part 1: 2004 Specification for the loose-fill BS EN 14316
products before installation. Thermal insulation products for buildings.
Part 2: 2013 Specification for the installed Expanded perlite (EP) products:
products. Part 1: 2004 Specification for bonded and
loose-fill products before
BS EN 14064 installation.
Thermal insulation in buildings. In-situ formed Part 2: 2007 Specification for the installed
loose-fill mineral wool (MW) products: products.
Part 1: 2010 Specification for the loose-fill
products before installation. BS EN 14317
Part 2: 2010 Specification for the installed Thermal insulation products for buildings.
insulation products. Exfoliated vermiculite (EV) products:
Part 1: 2004 Specification for bonded and
BS EN 14303: 2009 loose-fill products before
Thermal insulation products for building installation.
equipment and industrial installations. MW. Part 2: 2007 Specification for the installed
products.
BS EN 14304: 2009
Thermal insulation products for building BS EN 14318
equipment and industrial installations. Flexible Thermal insulating products for buildings.
elastomeric foam (FEF). Polyurethane and polyisocyanurate:
Part 1: 2013 Specification for the rigid foam
BS EN 14305: 2009 before installation.
Thermal insulation products for building Part 2: 2013 Specification for the installed
equipment and industrial installations. CG. insulation products.

BS EN 14306: 2009 BS EN 14319
Thermal insulation products for building Thermal insulation products for building
equipment and industrial installations. Calcium equipment and industrial installations. In-situ
silicate CS. formed dispensed rigid polyurethane (PUR) and
polyisocyanurate foam (PIR):
BS EN 14307: 2009 Part 1: 2013 Specification for the rigid foam
Thermal insulation products for building before installation.
equipment and industrial installations. XPS. Part 2: 2013 Specification for the installed
insulation products.
BS EN 14308: 2009
Thermal insulation products for building BS EN 14320
equipment and industrial installations. Thermal insulation products for building
Polyurethane foam (PUR) and polyisocyanurate equipment and industrial installations. In-situ
foam (PIR). formed sprayed rigid polyurethane and
polyisocyanarate foam:
BS EN 14309: 2009 Part 1: 2013 Specification for the rigid foam
Thermal insulation products for building before installation.
equipment and industrial installations. EPS. Part 2: 2013 Specification for the installed
insulation products.
BS EN 14313: 2009
Thermal insulation products for building
equipment and industrial installations.
Polyethylene foam (PEF).

BS EN 14314: 2009
Thermal insulation products for building
equipment and industrial installations. PF.

INSULATION MATERIALS 413

BS EN 14933: 2007 Part 2: 2013 Processing of the factory
Thermal insulation and lightweight fill products premixed EPS dry plaster.
for civil engineering applications. Expanded
polystyrene (EPS). BS EN 16069: 2012
Thermal insulation products for building. Factory
BS EN 14934: 2007 made products of polyethylene foam (PEF).
Thermal insulation and lightweight fill products Specification.
for civil engineering applications. Extruded
polystyrene foam (XPS). BS EN ISO 16283
Acoustics. Field measurement of sound insulation
BS EN 15101 in buildings and of building elements:
Thermal insulation products for building. In-situ Part 1: 2014 Airborne sound insulation.
formed loose fill cellulose (LFCI) products: pr Part 2: 2013 Impact sound insulation.
Part 1: 2013 Specification for the products pr Part 3: 2014 Façade sound insulation.
before installation.
Part 2: 2013 Specification for the installed PD ISO/TR 16344: 2012
insulation products. Energy performance of buildings. Common terms,
definitions and symbols for the overall energy
PD CEN/TR 15131: 2006 performance rating and certification.
Thermal performance of building materials.
pr BS EN 16491: 2012
BS EN 15265: 2007 Thermal insulation products for building. Factory
Energy performance of buildings. Calculation of made composite products. Specification.
energy needs for space heating and cooling using
dynamic methods. BS EN ISO 23993: 2010
Thermal insulation products for building
BS EN 15501: 2013 equipment and industrial installations.
Thermal insulation products for building Determination of design thermal conductivity.
equipment and industrial installations. Factory
made perlite (EP) and exfoliated vermiculite (EV) PAS 2030: 2012 Ed. 2
products. Improving the energy efficiency of existing
buildings. Specification.
BS EN 15599
Thermal insulation products for building PD 6680: 2002
equipment and industrial installations: Guidance on the new European Standards for
Part 1: 2010 In situ expanded perlite (EP) thermal insulation materials.
products before installation.
Part 2: 2010 Specification for the installed BUILDING RESEARCH ESTABLISHMENT
products. PUBLICATIONS

BS EN 15600 BRE Digest
Thermal insulation products for building
equipment and industrial installations: BRE Digest 453: 2000
Part 1: 2010 In situ exfoliated vermiculite Insulating glazing units.
(EV) products.
Part 2: 2010 Specification for the installed BRE Information papers
products.
BRE IP 4/01
pr EN 15603: 2013 Reducing impact and structure-borne sound in
Energy performance of buildings. Overarching buildings.
standard EPBD.
BRE IP 14/02
BS EN 16012: 2012 Dealing with poor sound insulation between new
Thermal insulation for buildings. Reflective dwellings.
insulation products.
BRE IP 3/03
BS EN 16025 Dynamic insulation for energy saving and
Thermal and/or sound insulating products in comfort.
building construction. Bound EPS ballasting:
Part 1: 2013 Requirements for factory BRE IP 2/05
premixed EPS dry plaster. Modelling and controlling interstitial
condensation in buildings.

414 INSULATION MATERIALS

BRE IP 15/05 BRE Reports
The scope for reducing carbon emissions from
housing. BR 262: 2002
Thermal insulation: Avoiding risks.
BRE IP 1/06
Assessing the effects of thermal bridging at BR 406: 2000
junctions and around openings. Specifying dwellings with enhanced sound
insulation: A guide.
BRE IP 18/11
Natural fibre insulation. An introduction to low- FB 61: 2013
impact building materials. Reducing thermal bridging at junctions when
designing and installing solid wall insulation.
BRE IP 4/13
Advanced thermal insulation technologies in the ADVISORY ORGANISATIONS
built environment.
British Rigid Urethane Foam Manufacturers Associ-
BRE Good building guides ation Ltd, 12a High Street East, Glossop, Derbyshire
SK13 8DA (01457 855884).
BRE GBG 37: 2000
Insulating roofs at rafter level: sarking insulation. Cork Industry Federation, 13 Felton Lea, Sidcup, Kent
DA14 6BA (0208 302 4801).
BRE GBG 43: 2000
Insulating profiled metal roofs. Eurisol-UK Mineral Wool Association, PO Box 35084,
London NW1 4XE (0207 935 8532).
BRE GBG 44: 2001
Insulating masonry cavity walls (Parts 1 and 2). European Phenolic Foam Association, Kingsley House,
Ganders Business Park, Kingsley, Bordon, Hamp-
BRE GBG 45: 2001 shire GU35 9LU (01420 471617).
Insulating ground floors.
Insulated Render and Cladding Association Ltd,
BRE GBG 50: 2002 6–8 Bonhill Street, London EC2A 4BX (0844
Insulating solid masonry walls. 2490040).

BRE GBG 68: 2006 National Insulation Association, 2 Vimy Court, Vimy
Installing thermal insulation: Good site practice Road, Leighton Buzzard, Bedfordshire LU7 1FG
(Parts 1 and 2). (01525 383313).

BRE GBG 83: 2014 Thermal Insulation Manufacturers & Suppliers Associ-
Sound insulation in dwellings. An introduction ation, Kingsley House, Ganders Business Park,
(Part 1). Kingsley, Bordon, Hampshire GU35 9LU (01420
471624).
BRE Good repair guide

BRE GRG 30: 2001
Remedying condensation in domestic pitched
tiled roofs.

14

SEALANTS, GASKETS
AND ADHESIVES

CONTENTS

Introduction 415 Fire-resistant sealants 420
Sealants 415 Foam sealants 421
416 Concrete joint fillers and sealants 421
Relative movement within buildings 417 Gaskets 421
Types of sealant 417 Waterstops 423
418 Adhesives 423
Plastic sealants 419 Types of adhesive 423
Elastoplastic sealants 419 References 426
Elastic sealants
Joint design

Introduction

Although used in relatively small quantities compared the performance characteristics of the sealant to the
with the load-bearing construction materials, sealants, requirements of the joint. Incorrect specification or
gaskets and adhesives play a significant role in the application, poor joint design or preparation is likely
perceived success or failure of buildings. A combination to lead to premature failure of the sealant. The standard
of correct detailing and appropriate use of these BS EN ISO 11600: 2003 + A1: 2011 classifies sealants
materials is necessary to prevent the need for expensive into type G for glazing applications and type F (façade)
remedial work. Many manufacturers are producing for other construction joints. For both types, classes are
solvent-free sealants and adhesives as environmentally defined by movement capability, modulus and elastic
friendly alternatives to the traditional solvent-based recovery (Fig. 14.1). The standard BS 8000–16: 1997 +
systems. A1: 2010 is the code of practice for sealing joints in
buildings with sealants.
Sealants
Key factors in specifying the appropriate sealant are:

Sealants are designed to seal the joints between adjacent • understand the cause and nature of the relative
building components while remaining sufficiently movement;
flexible to accommodate any relative movement. They
may be required to exclude wind, rain and airborne • match the nature and extent of movement to the
sound. A wide range of products is available matching appropriate sealant;

• match the sealant to the substrate;

416 SEALANTS, GASKETS, ADHESIVES

Sealants

Construction sealants (F) Glazing sealants (G)

Class 7.5 Class 12.5 Class 20 Class 25 Class 20 Class 25

P P E LM HM LM HM LM HM LM HM

Notes: F refers to façade, G to glazing.
Class number indicates the movement accommodation as a percentage.
P refers to plastic, E to elastic, LM to low modulus and HM to high modulus.

Fig. 14.1 Classification of sealants in construction

• ensure appropriate joint design, surface preparation movement is low, but moderate for glass, steel, brick,
and sealant application; stone and concrete, and relatively high for plastics and
aluminium. Such thermal movements are accentuated
• anticipate the exposure and temperature range; by the effects of colour, insulation and thickness of
• determine the required service life of the sealant. the material. Dark materials absorb solar radiation
and heat more quickly than light-reflective materials.
RELATIVE MOVEMENT WITHIN BUILDINGS In addition, well-insulated claddings respond quickly
to changes in solar radiation, producing rapid cyclical
The most common causes of movement in buildings expansion movements, whereas heavy construction
are associated with settlement, dead and live load effects materials respond more slowly but will still exhibit
including wind loading, fluctuations in temperature, considerable movements over an annual cycle. Typical
changes in moisture content and, in some cases, the thermal movements are shown in Table 14.1.
deteriorative effects of chemical or electrolytic action.
Depending on the prevailing conditions, the various Moisture movement
effects may be additive or compensatory.
Moisture movement falls into two categories: irreversi-
Settlement ble movements as new materials acclimatise to the
environment, and reversible cyclical movements due to
Settlement is primarily associated with changes in climatic variations. Many building materials, especially
loadings on the foundations during the construction concrete and mortars, exhibit an initial contraction
process, although it may continue for some time, during the drying-out process. Incorrectly seasoned
frequently up to five years after the construction is timber will also shrink but new bricks used too quickly
complete. Subsequent modifications to a building or its after manufacture will expand. After these initial
contents may cause further relative movement. Settle- effects, all materials which absorb moisture will expand
ment is usually slow and in one direction, creating a and contract to varying degrees in response to changes
shearing effect on sealants used across the boundaries. in their moisture content. Depending on climatic
conditions, moisture and thermal movements may
Thermal movement oppose or reinforce each other. Typical irreversible
and reversible moisture movements are shown in
All building materials expand and contract to some Table 14.2.
degree with changes in temperature. For timber the

SEALANTS, GASKETS, ADHESIVES 417

Table 14.1 Thermal movements of building materials Table 14.2 Moisture movements of typical building materials

Material Typical thermal Coefficient Material Reversible Irreversible
movement of linear (mm/m) (mm/m)
(mm/m for expansion
85°C change) per °C ϫ 10–6 Concrete 0.2–0.6 0.3–0.8 (shrinkage)
Aerated concrete 0.2–0.3 0.7–0.9 (shrinkage)
Masonry 1.2 10–14 Brickwork – clay 0.2 0.2–1.0 (expansion)
Concrete – standard aggregates 1.2 8–14 Brickwork – calcium silicate 0.1–0.5 0.1–0.4 (shrinkage)
Calcium silicate brickwork 1.0 6–12 Blockwork – dense 0.2–0.4 0.2–0.6 (shrinkage)
Concrete blockwork 0.7 8 Blockwork – aerated 0.2–0.3 0.5–0.9 (shrinkage)
Concrete – aerated 0.6 7–8 Glass-fibre reinforced cement 1.5 0.7 (shrinkage)
Concrete – limestone aggregate 0.5–0.7 5–8
Clay brickwork 1.0 7–12 Softwood 5–25 (60–90% relative humidity)
GRC Hardwood 7–32 (60–90% relative humidity)
Plywood 2–3 (60–90% relative humidity)

Plaster 1.5 18–21 (timber has no irreversible movement)
Dense plaster 1.4 16–18
Lightweight plaster Note:
Typical reversible and irreversible moisture movements of building materials
Metals 2.7 32 in use (measured in mm/m).
Zinc (along roll) (22 across roll)
2.5 29 Loading and deterioration
Lead 2.0 24
Aluminium 1.8 20–22 Movements associated with live loads such as
Titanium zinc 1.4 17 machinery, traffic and wind can cause rapid cyclical
Copper 1.4 18 movements within building components. The deteri-
Stainless steel (austenitic) 0.8 10 oration of materials, such as the corrosion of steel or
Stainless steel (ferritic) 1.4 17 sulphate attack on concrete, is often associated with
Terne coated stainless steel 1.0 12 irreversible expansion, causing movement of adjacent
Structural steel components. Concrete structures may exhibit creep,
which is gradual permanent deformation under load,
Stone and glass 0.9 9–11 over many years.
Glass 0.9 9–11
Slate 0.8 8–10 Types of sealant
Granite 0.8 7–12
Sandstone 0.4 4–6 There are three distinct types of sealant – plastic,
Marble 0.3 3–4 elastoplastic and elastic – each of which exhibits
Limestone significantly different properties which must be
matched to the appropriate application (BS 6213:
Plastics 8.0 83–95 2000).
ABS 6.0 40–80
PVC (rigid) 3.0 18–35 PLASTIC SEALANTS
GRP
Plastic sealants, which include general-purpose mastics,
Timber 0.5 4–6 allow only a limited amount of movement, but when
Wood (along grain) held in a deformed state they stress-relax. Elastic recov-
ery is limited to a maximum of 40%. Plastic sealants
Note: dry by the formation of a surface skin, leaving liquid
Typical thermal movements of building materials in use calculated for material encased to retain flexibility. However, with
a temperature variation of 85°C (e.g. –15 to +70°C ) (measured
in mm/m).

418 SEALANTS, GASKETS, ADHESIVES

time, the plastic core continues to harden; thus dura- Linseed oil putty
bility is related to the thickness of the material used.
Plastic sealants (Code P to BS EN ISO 11600: 2003 + Traditional putty contains a mixture of linseed oil
A1: 2011) are more suitable for locations in which the and inorganic fillers, which sets by a combination of
majority of movement is irreversible (BS 6213: 2000 + aerial oxidation of the oil and some absorption into
A1: 2010). the timber. A skin is produced initially, but the mass
ultimately sets to a semi-rigid material. Application is
Oil-based mastics with a putty knife onto primed timber. For applica-
tion to steel window frames, non-absorbent hardwoods
For oil-based mastics a 10 mm depth is required for and water-repellent preservative-treated softwoods,
optimum durability with a typical life expectancy of non-linseed oil putty is appropriate. Linseed oil putty
two to ten years. The effects of ultraviolet degradation should be painted within two weeks, whereas metal
are reduced by painting. Typical uses include sealing casement putty may be left for three months before
around window and door frames in traditional low-rise painting.
buildings. Oil-based mastics are not suitable for use
with PVC-U windows. (The typical movement accom- ELASTOPLASTIC SEALANTS
modation for oil-based mastics is 10%.)
Elastoplastic sealants will accommodate both slow
Butyl sealants cyclical movements and permanent deformations.
A range of products offer appropriately balanced
Butyl sealants are plastic but with a slightly rubbery strength, plastic flow and elastic properties for various
texture. They are used in small joints as a gap filler and applications.
general-purpose sealant where oil-based mastics would
dry too rapidly. Life expectancy is between 10 and 20 Polysulphide sealants
years if they are protected from sunlight by painting, but
only up to five years in exposed situations. (The typical Polysulphide sealants are available as one- or two-
movement accommodation for butyl sealants is 10%.) component systems. The one-component systems
have the advantage that they are ready for immediate
Acrylic sealants use. They cure relatively slowly by absorption of
moisture from the atmosphere, initially forming a
Water-based acrylic sealants are frequently used for skin and fully curing within two to five weeks. One-
internal sealing such as between plaster and new component systems are limited in their application
windows. The solvent-based acrylic sealants are dur- to joints up to 25 mm in width, but their ultimate
able for up to 20 years, with good adhesion to slightly performance is comparable to that of the two-com-
contaminated surfaces. They accommodate only ponent materials. Typical uses include structural
limited movement but produce a good external seal movement joints in masonry, joints between precast
around windows, both for new and remedial work. concrete or stone cladding panels and sealing around
(The typical movement accommodation for water- windows. The two-component polysulphide sealants
based and solvent-based acrylic sealants is 15% and require mixing immediately before use and fully
20% respectively.) cure within 24–48 hours. They are more suitable than
one-component systems for sealing joints which are
Polymer/bitumen sealants wider than 25 mm, have large movements, or are
subject to vandalism during setting. Uses include
Solvent-based bitumen sealants are generally suitable sealing joints within concrete and brickwork clad-
for low-movement joints in gutters and flashings. ding systems and also within poorly insulated light-
Hot-poured bitumen is used for sealing movement weight cladding panels. Polysulphides have a life
joints in asphalt and concrete floor slabs, although expectancy of 20–25 years. (The typical movement
compatibility with any subsequent floor coverings accommodation for polysulphide sealants is up to
should be verified. Non-hardening bitumen sealant 25% for one-part systems and up to 30% for two-
is used for blending in new and old bitumen roof part systems.)
membranes.

SEALANTS, GASKETS, ADHESIVES 419

ELASTIC SEALANTS Epoxy sealants

Elastic sealants are appropriate for sealing dynamic Epoxy sealants are appropriate for stress-relieving joints
joints where rapid cyclic movement occurs. They are where larger movements in compression than tension
often sub-classified as low or high modulus depend- are anticipated. Typical applications include floor joints
ing upon their stiffness. High-modulus (HM) sealants and the water sealing of tiling joints within swimming
are stiffer than low-modulus (LM) sealants. Low- pools. Two-component systems may be used for car
modulus sealants should be used where joints are parks subject to heavy low-speed traffic. (Epoxy sealants
exposed to long periods of compression or extension have a life expectancy of 10–20 years. The typical
and where the substrate material is weak. Elastic movement accommodation of epoxy sealants is within
sealants are categorised as Code E to BS EN ISO 11600: the range 5–15%.)
2003 + A1: 2011.
JOINT DESIGN
Polyurethane sealants
There are three forms of joint: butt, lap and fillet
Polyurethane sealants are available as one- or two- (Fig. 14.2). However, only butt and lap joints will
component systems. The products are highly elastic but accommodate movement. Generally, lap joints, in
surfaces should be carefully prepared and usually which the sealant is stressed in shear, will accommodate
primed to ensure good adhesion. Polyurethane sealants double the movement of butt joints in which the sealant
have good abrasion resistance and durability is good, is under tension or compression. Furthermore, lap
ranging from 20–25 years. Typical applications are joints tend to be more durable, as the sealant is partially
joints within glazing, curtain walling, lightweight clad- protected from the effects of weathering. However,
ding panels and floors. Two-component thixotropic lap joints are generally more difficult to seal than butt
sealants may be used in industrial locations subject to joints. Frequently, joints are made too narrow, either
hydrocarbon spillage. (The typical movement accom- for aesthetic reasons or due to miscalculation of com-
modation for polyurethane sealants is between 10% ponent tolerances. The effect is that extent of move-
and 30% depending on the modulus.) ment is excessive in proportion to the width of sealant,
causing rapid failure.
Silicone sealants
To correctly control the depth of the sealant and to
Silicone sealants are usually one-component systems prevent it from adhering to the back of the joint, a
which cure relatively quickly in air, frequently with the compressible back-up material, usually rectangular or
evolution of characteristic smells such as acetic acid. round closed-cell polyethylene, is inserted (Fig. 14.3).
Generally, silicone sealants adhere well to metals and The polyethylene acts as a bond breaker by not
glass, but primers may be necessary on friable or porous adhering to the sealant. Where the joint is filled with
surfaces, such as concrete or stone. Silicone sealants a filler board, such as impregnated fibreboard or
may cause staining on stonework which is difficult to corkboard, a plastic bond-breaker tape or closed-cell
remove. High-modulus silicone sealants are resilient. polyethylene strip should be inserted. Normally, the
Typical applications include glazing and curtain-wall depth of the sealant should be half the width of the
systems, movement joints in ceramic tiling and around joint for elastic and elastoplastic sealants and equal to
sanitary ware. Low-modulus silicone sealants are very the width of the joint for plastic sealants. A minimum
extensible and are appropriate for use in joints subject depth of 6 mm is normally required. The minimum
to substantial thermal or moisture movement. Typical width of the joint is calculated from the maximum total
applications are the perimeter sealing of PVC-U and relative movement (TRM) to be accommodated and
aluminium windows, and also cladding systems. the movement accommodation factor (MAF); that is,
Specialist silicone sealants will withstand a working the extensibility of the sealant to be used. Where
temperature of 300°C. Silicone sealants are durable insufficient depth is available to insert a polyethylene
with life expectancies within the range of 25–30 years. foam strip, a tape bond breaker should be inserted at
(The typical movement accommodation for silicone the back of the joint.
sealants ranges from 20%–70% depending on the
modulus.)

420 SEALANTS, GASKETS, ADHESIVES

Fig. 14.3 Typical sealant systems

Fig. 14.2 Butt, lap and fillet joints stonework is being sealed, non-staining silicone sealants
must be used to prevent the migration of plasticiser into
Minimum joint width calculation (BS 6093: 2006 + A1: the stone, which could cause discoloration. Sealants
2013): to floor joints need to be tough, and therefore wider to
accommodate the necessary movements and recessed
Total relevant movement (TRM) = 3 mm to prevent mechanical damage. Alternatively, propri-
etary mechanical jointing systems should be used.
Movement accommodation = 25%
factor (MAF) Colour matching

Width of sealant to accommodate = 3/0.25 + 3 While most sealants, except for the black bituminous
products, are available in white, translucent, greys
movement = 15 mm. and browns, the silicone sealants appropriate for use
around kitchen and bathroom units are available in a
In order to obtain good adhesion, the joint surfaces wide range of colours. For these purposes, fungicides
should be prepared by the removal of contaminants, are often included within the formulation.
loose material or grease and by the application of a
primer if specified by the sealant manufacturer. Most FIRE-RESISTANT SEALANTS
sealants are applied directly by gun application,
although tooled, poured and tape/strip sealants are also Many fire-resistant sealants are based on the use of
used. Tooling helps to remove air bubbles entrained in intumescent materials which expand copiously in fire.
two-component mixes; if left, air bubbles would reduce The intumescent components commonly used are
the durability of the seal. Externally, recessed cladding either ammonium phosphate, hydrated sodium silicate
joints show less staining than flush joints, although or intercalated graphite (layers of water and carbon),
the usual finish is a slightly concave surface. Where and these are incorporated into the appropriate sealant.
Intumescent oil-based mastics and acrylic sealants are

SEALANTS, GASKETS, ADHESIVES 421

suitable for sealing low-movement joints around fire subdivided into self-levelling (sl) or non-sag (ns) types.
check doors. For the fire-resistant sealing of structural An additional classification A, B, C or D relates to
movement joints, fire-resistant grades of low-modulus increasing level of resistance to chemicals. Standard
silicone, two-part polysulphide and acrylic sealants hot-applied joint sealants are classified as elastic
are available. Maximum fire resistance is obtained (high extension) Type N1, and normal (low extension)
if the sealant is applied to both faces of the joint, with Type N2. Where fuel resistance is also required, the
mineral wool or glass fibre insulation in the void space. higher specification grades F1 and F2 are necessary.
Four hours’ fire resistance with respect to both integrity
and insulation may be achieved for a 20 mm-wide Gaskets
movement joint within 150 mm concrete (BS 476–20:
1987). The low-modulus silicone is appropriate for Gaskets are lengths of flexible components of various
sealing fire-resisting screens, curtain walls, claddings profiles, which may be solid or hollow and manu-
and masonry subject to movement. The two-part poly- factured from either cellular or non-cellular materials.
sulphide is designed for use in concrete and masonry They are held in place either by compression or
fire-resisting joints. Acrylic sealants are appropriate encapsulation into the adjacent building materials,
over a wide range of materials but where timber is and maintain a seal by pushing against the two surfaces
involved an allowance must be made for its loss by (Fig. 14.4). Typical applications include the weather
charring. sealing of precast cladding units and façade systems.
Within precast concrete, glassfibre-reinforced poly-
Intumescent fillers manufactured from acrylic ester (GRP) or glassfibre-reinforced concrete (GRC)
emulsions with inert fillers and fire-retardant additives cladding units, the gaskets are typically inserted into
may be applied either by gun or trowel to fill voids recessed open-drained joints. The gaskets therefore act
created around service ducts within fire-resistant walls. as a rain barrier, but because they do not necessarily fit
Four hours of fire resistance may be achieved with tightly along their full length, they may be backed up
these materials. Intumescent tapes are appropriate for by a compressed cellular foam wind penetration seal.
application within structural movement joints. Most Gaskets should not be either stretched or crammed in
intumescent sealants are now low-smoke and evolve no during insertion as they will subsequently shrink, leav-
halogenated products of combustion in fire situations. ing gaps, or pop out, causing failure.
(The typical movement accommodation for intume-
scent acrylic sealants is 15%.) In glazing and related curtain-walling systems,
gaskets may be applied as capping seals, retained by
FOAM SEALANTS appropriate profiles within the mullions and transoms;
alternatively, the gaskets may be recessed within the
Compressible strips of closed-cell PVC and poly- joints of the glazing system to give narrower visual
ethylene, or open-cell polyurethane foams, coated on effect to the joint. Some glazing gaskets of H- or
one or both edges with pressure-sensitive adhesive, U-sections are sealed with a zipper or filler strip which
are used to seal thermal movement and differential is inserted into the profile, compressing the material
settlement joints, gaps around window and door into an air- and watertight seal. Gaskets and weather-
frames, and in air-conditioning ductwork. Strips may stripping for use on doors, windows and curtain
be uniform in section or profiled for particular appli- walling are classified by a letter and digit code which
cations. Aerosol-dispensed polyurethane foam is widely defines the use and key physical properties of the
used as an all-purpose filler. It is available either as foam particular product, enabling appropriate specification
or as expanding foam, and acts as an adhesive, sealant, (Table 14.3).
filler and insulator.
The standard materials for gaskets used in
CONCRETE JOINT FILLERS AND SEALANTS construction are neoprene which is highly elastic,
ethylene propylene diene monomer (EPDM) which
Concrete joint fillers for use in pavements are specified has better weathering characteristics than neoprene,
by the standards BS EN 14188: 2004, Parts 1 and 2 for and silicone rubbers which are highly resistant to
hot and cold application sealants, respectively. Sealants ultraviolet light, operate over a wide range of tem-
for cold application are classified as single-component peratures and are available in almost any colour.
systems (S) or multi-component systems (M), and

422 SEALANTS, GASKETS, ADHESIVES

Fig. 14.4 Typical gaskets for cladding and glazing systems Fig. 14.5 Concrete waterstop seals

Cruciform section gaskets of polychloroprene rubber Dry glazing strips are based on elastomeric poly-
are suitable for vertical joints between precast concrete mers, typically EPDM or butyl rubber. Usually, the
panels. synthetic rubber strip has a self-adhesive backing which
adheres to the rebate upstand. With external beading,
Proprietary systems offer watertight expansion the dry glazing strip may also be applied to each bead,
jointing for horizontal surfaces, such as roof car parks which is then fixed with suitable compression to ensure
and pedestrian areas. Systems usually combine complex a good seal to the glass. The performance requirements
aluminium or stainless steel profiles with extruded and classification for gaskets and weatherstripping for
synthetic rubber inserts. Materials can withstand doors, windows and curtain walling are described in the
high loads, with good resistance to bitumen and salt standard BS EN 12365–1: 2003.
water.

Table 14.3 Classification of gaskets and weatherstripping to BS EN 12365–1: 2003 (letter and five-number code)

Letter (G or W) Digit 2 Digit 3 Digit 4 Digit 5 Digit 6

Category Working Compression Working Deflection Recovery
range force temperature recovery after
(mm) (KPa) range (%) ageing
(°C) (%)

Gasket (G) 9 grades 9 grades 6 grades 8 grades 8 grades
Weatherstripping (W) identified identified identified identified identified
(1–9) (1–9) (1– 6) (0–7) (1–8)

SEALANTS, GASKETS, ADHESIVES 423

WATERSTOPS Table 14.4 Classification of tile adhesives by composition and
properties (BS EN 12004: 2007 + A1: 2012)
Waterstops for embedding into in situ concrete for
sealing movement and construction joints are manu- Classification Composition and properties
factured in PVC or rubber according to the required
movement (Fig. 14.5). Sections are available in long Type C cementitious adhesive – hydraulic binding resin
extruded lengths and factory-produced intersections.
Applications include water-containing structures and Type D dispersion adhesive – aqueous organic polymer
water exclusion from basements. Waterstops placed
centrally within concrete will resist water pressure from resin
either side, but externally positioned waterstops, not
encased below the concrete slab or within permanent Type R reaction resin adhesive – one- or two-component
concrete shuttering, will only resist water pressure
from the outer face. Hydrophilic waterstops, including synthetic resin
modified chloroprene rubber or sodium bentonite/
butyl rubber, expand in contact with water to form Class 1 normal adhesive
the seal. Their typical application is within concrete Class 2 improved adhesive
construction joints. PVC waterstops incorporating Class F fast-setting adhesive
hydrophilic elements are also available. Class T reduced slip adhesive
Class E extended open time adhesive
Adhesives Class S1 deformable adhesive
Class S2 highly deformable adhesive
TYPES OF ADHESIVE
relating to enhanced adhesive properties, faster
The traditional adhesives based on animal and setting, reduced slip or extended open time (the time
vegetable products have largely been superseded by between spreading the adhesive and applying the tiles)
synthetic products manufactured by the polymer (Table 14.4). Dispersion adhesives are the ready-for-use
industry, except for casein, manufactured from aqueous polymer dispersions, while the reaction resin
skimmed milk, which is currently used as a timber adhesives are one- or two-component systems which
adhesive (BS EN 12436: 2002). The range of adhesives set by chemical reaction. Tile adhesives with no more
is under constant development and particular appli- than 1% organic material are classified for fire resist-
cations should always be matched to manufacturers’ ance as Class A1 or A1fl.
specifications. Special notice should be taken of
exclusions where materials and adhesives are incom- Ceramic wall tile adhesives
patible; also to safety warnings relating to handling
and the evolution of noxious fumes or flammable Wall tile adhesives are usually polyvinyl acetate (PVA),
vapours. Adhesives are more efficient when bonding acrylic- or cement-based compositions. The standard
components subject to shear forces rather than direct PVA thin-bed adhesives, typically to 3 mm, will only
tension. They are least efficient against the peeling tolerate moisture, whereas the thin bed water-resistant
stresses. Most adhesives have a shelf life of 12 months acrylic-based adhesives are suitable for fixing wall tiles
when stored unopened under appropriate conditions. and mosaics in damp and wet conditions associated, for
The pot life after mixing the two-component systems example, with domestic showers. Some acrylic-based
ranges from a few minutes to several hours. products evolve ammonia on setting. The water-
resistant cements and polymer-modified cement
Tile adhesives products are appropriate both for internal and external
use and can usually be applied with either thin or thick
The standard BS EN 12004: 2007 + A1: 2012 classifies bedding. The polymer-modified cement adhesives are
adhesives for tiles into three types: cementitious (C), also suitable for fixing marble, granite and slate tiles up
dispersion (D) and reaction resin (R). Each of these to 15 mm thick. For chemical resistance thin bed epoxy
types may have further characteristics defined by classes resin-based adhesives are available. In all cases the
substrate must be sound, with new plaster, brickwork
and concrete fully dried out for two to six weeks.
Plasterboard and timber products must be adequately
fixed at 300 mm centres horizontally and vertically
to ensure rigidity. In refurbishment work, flaking or
multi-layered paint should be removed and glazed

424 SEALANTS, GASKETS, ADHESIVES

surfaces made good. Where the tile adhesive is classified evolved. Expanded polystyrene tiles may be adversely
as waterproof either acrylic- or cement-based, it may affected by solvent-based formulations.
be used as the grouting medium. Alternatively, equiva-
lent waterproof grouting is available in a wide range of Vinyl floor tile and wood block adhesives
colours to blend or contrast with the wall tiles. Epoxy-
resin tile grout is available for very wet conditions. Most vinyl floor tile and wood block adhesives are
Two-component thixotropic polyurethane non-slump based on either rubber/bitumen, rubber/resin or
tile adhesives prevent slippage during wall tiling. modified bitumen emulsions. Alternative materials
include polyurethane and epoxy-polyurethane adhe-
Ceramic floor tile adhesives sives. In all cases it is essential that the sub-floor is dry,
sound, smooth and free from any contamination which
The majority of ceramic floor tile adhesives are cement- would affect the adhesion. Where necessary, cement/
based, used either as thick bed (up to 25 mm) or thin acrylic or cement/latex floor levelling compound
bed according to the quality of the substrate. Standard should be applied to concrete, asphalt or old ceramic
products are suitable for fixing ceramic tiles, quarries, tiled floors. Some cement/latex materials evolve
brick slips, stone and terrazzo to well-dried-out con- ammonia during application.
crete or cement/sand screed. Where suspended timber
floors are to be tiled, they must be well ventilated and Wood adhesives
strong enough to support the additional dead load. An
overlay of 12 mm exterior grade plywood, primed with Wood joints should generally be in close contact with
bonding agent and screwed at 200 mm centres, may be a gap of less than 0.15 mm, but so-called gap-filling
necessary. In refurbishment work it is better to remove adhesives satisfactorily bond up to 1.3 mm. Poly vinyl
all old floor finishes, but ceramic floor tiles may be fixed acetate (PVA) wood glues are widely used for most
over cleaned ceramic or possibly primed vinyl tiles, on-site work and in the factory assembly of mortice
provided that all loose material is first removed. and tenon joints for doors, windows and furniture. The
white emulsion sets to a colourless translucent thermo-
Cement-based grouting can be pigmented to the plastic film, giving a bond of similar strength to the
required colour, but care must be taken to ensure that timber itself, but is insufficient for bonding load-
excess grout is removed from the surface of the tiles bearing structural members. Components should be
before staining occurs. Thin bed two-component clamped into position for up to 12 hours to ensure
epoxy-based adhesives are more water and chemical maximum bonding, although this may be reduced by
resistant than the standard cement-based products increasing the temperature. Waterproof PVA adhesives,
and are appropriate for use where repeated spillage is which partially cross-link on curing, are suitable for
likely from industrial processes. Where there is likely protected external use but not immersion in water.
movement of the substrate, two-component rubber- PVA adhesives generally retain their strength up to
based adhesives are generally appropriate. Two-com- 60°C and do not discolour the timber, except by contact
ponent polyurethane systems are also appropriate for with ferrous metals.
stone, tile and mosaic flooring.
The thermosetting wood resins are mainly two-
Contact adhesives component systems based on phenolic compounds,
such as urea, melamine, resorcinol or phenol, which
Contact adhesives based on polychloroprene rubber, cure with formaldehyde to produce load-bearing
either in organic solvents or aqueous emulsions, are adhesives (BS EN 301: 2013). Most formulations
normally suitable for bonding decorative laminates, require the mixing of the resin and hardener, but a
and other rigid plastics such as PVC and ABS to timber, premixed dry powder to which water is added is
timber products and metals. The adhesive is usually also available. Structural resin-based adhesives are
applied to both surfaces; the solvent or emulsion is designated for exterior (Service Class 1, 2 or 3 to BS
allowed to become touch dry, prior to bringing the two EN 1995–1-1: 2004) or high-temperature (70/90°C)
surfaces into contact, when an immediate strong bond exposure (Type I), or internal Service Class 1 use (Type
is produced. The aqueous emulsion products can also II). Melamine formaldehyde adhesives will not resist
be suitable for fixing sealed cork and expanded poly- prolonged exposure to weathering. Urea formalde-
styrene, and have the advantage that no fumes are hyde adhesives are generally moisture resistant or for

SEALANTS, GASKETS, ADHESIVES 425

interior use only. Certain timber fire-retardant and close-fitting joints and higher viscosities for the larger
preservative treatments reduce the efficiency of timber gaps.
adhesives, although generally those based on phenol
formaldehyde/resorcinol formaldehyde are unaffected. Hot-melt adhesives

Wallpaper adhesives Hot-melt adhesives for application by glue gun are
usually based on the thermoplastic copolymer, ethylene
Standard wallpaper adhesives are based on methyl vinyl acetate (EVA). Formulations are available for
cellulose, a white powder which is water soluble giving joining materials to either flexible or rigid substrates.
a colourless solution. For fixing the heavier papers Generally, the adhesive should be applied to the less
and decorative dado strips, poly vinyl acetate is an easily bonded surface first (e.g. the harder or smoother
added component. Cold water starch is also available surface) and then the two components should be
as both a wall-sizing agent and wallpaper adhesive. pressed together for at least one minute. Where metals
Most wallpaper pastes contain fungicide to inhibit are to be bonded they should be pre-warmed to prevent
mould growth. The standard BS 3046: 1981 describes rapid dissipation of the heat. Similar adhesives are used
five types of adhesive ranging from low solids to high in iron-on edging veneers for plastic- and wood-faced
wet and dry strength with added fungicide. particleboard.

Epoxy resin adhesives Bitumen sheet roofing adhesives

Epoxy resins are two-component, cold-curing adhe- Bitumen adhesives are available for hot application,
sives which produce high-strength, durable bonds. emulsion or in hydrocarbon solvent for the cold
Most require equal quantities of the resin and hardener bonding of bituminous sheet roofing. The adhesives
to be mixed and various formulations are available should be poured and spread by trowel to avoid air
giving curing times ranging from minutes to hours. pockets, which may cause premature delamination of
Strong bonds can be obtained to timber, metal, glass, the sheet from the substrate. Excess bitumen should be
concrete, ceramics and rigid plastics. Epoxy resins may removed, as it may stain adjacent materials.
be used internally or externally and are resistant to oils,
water, dilute acids, alkalis, and most solvents except for Plastic pipe adhesives
chlorinated hydrocarbons. Epoxy resins are frequently
used for attaching stainless steel fixings into stone and Solvent-based vinyl resin adhesives are used for
brick slips prior to their casting into concrete cladding bonding PVC-U and ABS pipes and fittings. The
panels. Epoxy flooring adhesives may be used for adhesive is brush-applied to both components which
bonding vinyl floor finishes in wet service areas and to are then united and slightly rotated to complete the seal.
metal surfaces. Thixotropic two-part epoxy adhesives Curing is rapid but in cold-water supply systems, water
are designed to inject into cracks and holes in timber pressure should not be applied for several hours.
and masonry.
Gap-filling adhesive
Cyanoacrylate adhesives
Gun grade gap-filling adhesives, either solvent-borne
Cyanoacrylates are single-component adhesives rubber/synthetic rubber resins with filler reinforcement
which bond components held in tight contact within or solvent-free polymer emulsion systems, are versatile
seconds. A high-tensile bond is produced between in their applications. They are generally formulated to
metals, ceramics, most plastics and rubber. The curing bond timber, timber products, decorative laminates,
is activated by adsorbed moisture on the material sheet metals, PVC-U and rigid insulating materials
surfaces, and only small quantities of the clear adhesive (except for polystyrene) to themselves and also to
are required. The bond is resistant to oil, water, sol- brickwork, blockwork, concrete, plaster and GRP.
vents, acid and alkalis but does not exhibit high Typical applications include the fixing of decorative
impact resistance. A range of adhesive viscosities is wall panels, dado rails, architraves and skirting boards
manufactured to match to particular applications. without nailing or screwing. Surfaces to be bonded
Generally the low-viscosity material is appropriate for must be sound and clean, but the gap-filling properties

426 SEALANTS, GASKETS, ADHESIVES

of the products can allow fixing to uneven surfaces. The Part 2: 1992 Code of practice for application
materials have good immediate adhesion, and allow and use of joint sealants.
the components to be adjusted into position.
Part 3: 1993 Methods of test.
PVA bonding agent and sealant BS 3046: 1981

Polyvinyl acetate (PVA) is a versatile material which Specification for adhesives for hanging flexible
will act not only as an adhesive as described above but wall coverings.
also as a bonding agent or surface sealant. As a bonding BS 3712
agent it will bond cement screeds, rendering and plaster Building and construction sealants:
to suitable sound surfaces without the requirement for
a good mechanical key. PVA will seal porous concrete Part 1: 1991 Method of test of homogeneity,
surfaces to prevent dusting. relative density and penetration.

References Part 2: 1973 Methods of test for seepage,
staining, shrinkage, shelf-life
FURTHER READING and paintability.

Cognard, P. 2005: Handbook of adhesives and sealants: Part 3: 1974 Methods of test for application
Basic concepts and high tech bonding. Netherlands: life, skinning properties and
Elsevier. tack-free time.

Dunn, D.J. 2004: Handbook of adhesives and sealants: Part 4: 1991 Methods of test for adhesion in
Applications and markets. Shrewsbury: RAPRA peel.
Technology.
BS 4255
Intumescent Fire Seals Association. 1999: Sealing Rubber used in preformed gaskets for weather
apertures and service penetrations to maintain fire exclusion from buildings:
resistance. Princes Risborough: IFSA. Part 1: 1986 Specification for non-cellular
gaskets.
Klosowski, J. 2014: Sealants in construction, 2nd edn.
Abingdon: CRC Press. BS 5212
Cold applied joint sealants for concrete
Mittal, K. and Pizzi, A. 2009: Handbook of sealant pavements:
technology. Abingdon: CRC Press. Part 1: 1990 Specification for joint sealants.
Part 2: 1990 Code of practice for application
Petrie, E.M. 2007: Handbook of adhesives and sealants, and use of joint sealants.
2nd edn. USA: McGraw-Hill Professional. Part 3: 1990 Methods of test.

SPRA. 2009: The use of sealants. London: Single Ply BS 5270
Roofing Association. Bonding agents for use with gypsum plaster and
cement:
STANDARDS Part 1: 1989 Specification for polyvinyl
acetate (PVAC) emulsion
BS 476 bonding agents for indoor use
Fire tests on building materials and structures: with gypsum building plasters.
Part 20: 1987 Method for determination of
the fire resistance of elements BS 5385
of construction. Wall and floor tiling:
Part 1: 2009 Design and installation of
BS 1203: 2001 internal ceramic, natural stone
Hot-setting phenolic and aminoplastic wood and mosaic wall tiling in normal
adhesives. internal conditions. Code of
practice.
BS 2499 Part 2: 2006 Design and installation of
Hot-applied joint sealant systems for concrete external ceramic and mosaic
pavements: wall tiling in normal conditions.
Code of practice.
Part 3: 2007 Design and installation of
internal and external ceramic
floor tiles and mosaics in

SEALANTS, GASKETS, ADHESIVES 427

normal conditions. Code of Part 3: 2010 Terms, definitions and
practice. specifications for grouts.
Part 4: 2009 Design and installation of
ceramic and mosaic tiling in BS ISO 13640: 1999
special conditions. Code of Building construction. Jointing products.
practice. Specifications for test substrates.
Part 5: 2009 Design and installation of
terrazzo, natural stone and BS ISO 16938
agglomerated stone tile and slab Building construction. Determination of staining
flooring. Code of practice. of porous substrates by sealants used in joints:
BS ISO 5892: 2013 Part 1: 2008 Test with compression.
Rubber building gaskets. Materials for preformed Part 2: 2008 Test without compression.
solid vulcanized structural gaskets. Specification.
BS 6093: 2006 BS ISO 17087: 2006
Design of joints and jointing in building Specification for adhesives used for finger joints in
construction. Guide. non-structural lumber products.
BS 6213: 2000
Selection of constructional sealants. Guide. BS ISO 18280: 2010
BS 6446: 1997 Plastics. Epoxy resins. Test methods.
Specification for manufacture of glued structural
components of timber and wood based panel BS EN 204: 2001
products. Classification of thermoplastic wood adhesives for
BS 6576: 2005 non-structural applications.
Code of practice for diagnosis of rising damp
within walls of buildings and installation of BS EN 205: 2003
chemical damp-proof courses. Adhesives. Wood adhesives for non-structural
BS 8000 applications. Determination of tensile shear
Workmanship on building sites: strength of lap joints.
Part 11: 2011 Internal and external wall and
floor tiling. Ceramic and BS EN 301: 2013
agglomerated stone tiles, natural Adhesives, phenolic and aminoplastic, for load-
stone and terrazzo tiles, slabs bearing timber structures. Classification and
and mosaics. Code of practice. performance requirements.
Part 12: 1989 Code of practice for decorative
wall coverings and painting. BS EN 302
Part 16: 1997 Code of practice for sealing Adhesives for load-bearing timber structures:
joints in buildings using Part 1: 2013 Determination of longitudinal
sealants. tensile shear strength.
BS 8203: 2001 Part 2: 2013 Determination of resistance to
Code of practice for installation of resilient floor delamination.
coverings. Part 3: 2013 Determination of effect of acid
BS 8449: 2005 damage to wood fibres.
Building and construction sealants with Part 4: 2013 Determination of the effects of
movement accommodation factors greater than wood shrinkage on shear
25%. Method of test. strength.
pr BS ISO 11617: 2013 Part 5: 2013 Determination of maximum
Buildings and civil engineering works. Sealants. assembly time.
BS ISO 13007 Part 6: 2013 Determination of minimum
Ceramic tiles. Grouts and adhesives: pressing time.
Part 1: 2010 Terms, definitions and Part 7: 2013 Determination of the working
specifications for adhesives. life under referenced
conditions.

BS EN 923: 2005
Adhesives. Terms and definitions.

BS EN 1323: 2007
Adhesives for tiles.

BS EN 1903: 2008
Adhesives. Test method for adhesive for plastic or
rubber floor coverings or wall coverings.

428 SEALANTS, GASKETS, ADHESIVES

BS EN 1965 BS EN ISO 11432: 2005
Structural adhesives. Corrosion: Building construction. Sealants. Determination
Part 1: 2011 Determination and classification of resistance to compression.
of corrosion to a copper
substrate. BS EN ISO 11600: 2003
Part 2: 2011 Determination and classification Building construction. Jointing products.
of corrosion to a brass substrate. Classification and requirements for sealants.

BS EN 1966: 2009 BS EN 12002: 2008
Structural adhesives. Characterisation of a surface Adhesives for tiles. Determination of transverse
by measuring adhesion. deformation for cementitious adhesives and
grouts.
BS EN ISO 6927: 2012
Building and civil engineering works. Sealants. BS EN 12004: 2007
Vocabulary. Adhesives for tiles. Requirements, evaluation of
conformity, classification and designation.
BS EN ISO 7389: 2003
Building construction. Jointing products. BS EN 12152: 2002
Determination of elastic recovery of sealants. Curtain walling. Air permeability. Performance
requirements and classification.
BS EN ISO 7390: 2003
Building construction. Jointing products. BS EN 12154: 2000
Determination of resistance to flow of sealants. Curtain walling. Watertightness. Performance
requirements and classification.
BS EN ISO 8339: 2005
Building construction. Sealants. Determination of BS EN 12365
tensile properties. Building hardware. Gaskets and weather stripping
for doors, windows shutters and curtain
BS EN ISO 8340: 2005 walling:
Building construction. Sealants. Determination of Part 1: 2003 Performance requirements and
tensile properties at maintained extension. classification.
Part 2: 2003 Linear compression force test
BS EN ISO 8394: 2010 methods.
Building construction. Jointing products. Part 3: 2003 Deflection recovery test
Determination of extrudability of sealants. method.
Part 4: 2003 Recovery after accelerated
BS EN ISO 9046: 2004 ageing test method.
Building construction. Jointing products.
Determination of adhesion/cohesion properties of BS EN 12436: 2002
sealants at variable temperatures. Adhesives for load-bearing timber structures.
Casein adhesives. Classification and performance
BS EN ISO 9047: 2003 requirements.
Building construction. Jointing products.
Determination of adhesion/cohesion properties of BS EN 12765: 2001
sealants at constant temperature. Classification of thermosetting wood adhesives
for non-structural applications.
BS EN ISO 9664: 1995
Adhesives. Test methods for fatigue properties of BS EN 12860: 2001
structural adhesives in tensile shear. Gypsum based adhesives for gypsum blocks.
Definitions, requirements and test methods.
BS EN ISO 10590: 2005
Building construction. Sealants. Determination of BS EN 13022
tensile properties of sealants at maintained Glass in building. Structural sealant glazing:
extension. Part 1: 2014 Glass products for structural
sealant glazing systems.
BS EN ISO 10591: 2005 Part 2: 2014 Assembly rules.
Building construction. Sealants. Determination of
adhesion/cohesion properties. BS EN 13119: 2007
Curtain walling. Terminology.
BS EN ISO 11431: 2002
Building construction. Jointing products. BS EN 13415: 2010
Determination of adhesion/cohesion properties of Test of adhesives of floor coverings.
sealants after exposure to heat, water and artificial
light through glass.

SEALANTS, GASKETS, ADHESIVES 429

BS EN 13501–1: 2007 bearing timber structures. Classification and
Classification using test data from reaction to fire performance requirements.
tests. BS EN 15434: 2006
Glass in building. Product standard for structural
BS EN 13880: 2004 and/or UV resistant sealant.
Hot applied sealants. Tests. BS EN 15466
Primers for cold and hot applied joint sealants:
BS EN 13888: 2009
Grouts for tiles. Requirements, evaluation of Part 1: 2009 Determination of
conformity, classification and designation. homogeneity.

BS EN 14080: 2013 Part 2: 2009 Determination of resistance
Timber structures. Glued laminated timber and to alkali.
glued solid timber. Requirements.
BS EN 15497: 2014
BS EN 14187 Structural finger jointed solid timber.
Cold applied joint sealants. Test methods: Performance requirements and minimum
Part 9: 2006 Function testing of joint production requirements.
sealants.
BS EN 15651
BS EN 14188 Sealants for non-structural use in joints in
Joint fillers and sealants: buildings and pedestrian walkways:
Part 1: 2004 Specification for hot applied Part 1: 2012 Sealants for façade elements.
sealants. Part 2: 2012 Sealants for glazing.
Part 2: 2004 Specification for cold applied Part 3: 2013 Sealants for sanitary joints.
sealants. Part 4: 2012 Sealants for pedestrian
Part 3: 2006 Specification for preformed walkways.
joint sealants. Part 5: 2012 Evaluation of conformity and
Part 4: 2009 Specification for primers to be marking.
used with joint sealants.
BS EN 15870: 2009
BS EN 14496: 2005 Adhesives. Determination of tensile strength of
Gypsum based adhesives for thermal/acoustic butt joints.
insulation composite panels and plasterboards.
BS EN 16254: 2013
BS EN 14680: 2006 Adhesives. Emulsion polymerized isocyanate (EPI)
Adhesives for non-pressure plastic piping systems. for load-bearing timber structures. Classification
Specifications. and performance requirements.

BS EN 14840: 2005 pr EN 16759: 2014
Joint fillers and sealants. Test methods for Structural sealant glazing systems (SSGS).
preformed joint seals.
BS EN 28394: 1991
BS EN 15274: 2007 Building construction. Jointing products.
General purpose adhesives for structural assembly. Determination of extrudability of one-component
Requirements and test methods. sealants.

BS EN 15275: 2007 BS EN 29048: 1991
Structural adhesives. Characterisation of Building construction. Jointing products.
anaerobic adhesives. Determination of extrudability of sealants under
standardized apparatus.
BS EN 15416: 2006
Adhesives for load bearing timber structures BUILDING RESEARCH ESTABLISHMENT
other than phenolic and aminoplastic: PUBLICATIONS
Part 2: 2007 Test methods. Static load test.
Part 3: 2007 Test methods. Creep BRE Digests
deformation.
Part 4: 2006 Test methods. Open assembly BRE Digest 463: 2002
time. Selecting building sealants with ISO 11600.
Part 5: 2006 Test methods. Conventional
pressing time.

BS EN 15425: 2008
Adhesives, one component polyurethane, for load

430 SEALANTS, GASKETS, ADHESIVES

BRE Digest 469: 2002 ADVISORY ORGANISATION
Selecting gaskets for construction joints.
British Adhesives and Sealants Association, 5 Alderson
BRE Information papers Road, Worksop, Nottinghamshire S80 1UZ (01909
480888).
BRE IP 12/03
VOC emissions from flooring adhesives.

BRE IP 4/12
Bio-resins in construction.

15

PAINTS, WOOD STAINS,
VARNISHES AND COLOUR

CONTENTS

Introduction 431 Paints 437
Colour 431 Components of paints 438
431 Paint systems 438
British Standards system 432 Special paints 439
Natural Colour System 435 441
RAL Classic System 435 Wood finishes 441
RAL Design System 435 Wood stains 441
Colour Palette notation 437 Varnishes 442
Pantone 437 Natural wood finishes 442
Munsell 437 Oils 442
Visual comparison of paint colours
References

Introduction Colour

As colour is an important factor in the description BRITISH STANDARDS SYSTEM
of surface finishes including paints, wood stains and
varnishes, the key elements of the British Standards, The British Standards BS 5252: 1976 (237 colours with
Natural Colour System, RAL, Colour Palette, Pantone approximate Munsell references) and BS 4800: 2011
and Munsell are described. Colour is a key feature of (122 colours) define colour for building purposes
architectural design, as illustrated in Figure 15.1 by and paints, respectively. A specific colour is defined by
the vivid spectrum colour sequence in Barajas Airport, the BS 4800 framework with a three-part code consist-
Madrid by Rogers Stirk Harbour + Partners and ing of hue (two digits, 00–24), greyness (letter A–E)
Estudio Lamela. Large electronic panels (Fig. 15.2) and weight (two further digits) (Fig. 15.3). Hue is
operated by programmed LED systems can create the attribute of redness, yellowness, blueness, etc., and
dynamic colour patterns or text sequences, creating the framework consists of 12 rows of hue in spectral
eye-catching façades. sequence plus one neutral row. Greyness is a measure
of the grey content of the colour at five levels from
the maximum greyness Group A, to clear Group E.
The third attribute, weight, is a subjective term which
incorporates both lightness (reflectivity to incident
light) and greyness. Within a given column, colours

432 PAINTS, WOOD STAINS, VARNISH, COLOUR

Fig. 15.1 Colour feature – Barajas Airport, Madrid. Architects:
Rogers Stirk Harbour + Partners. Photograph: AENA / Manuel Renau

have the same weight, but comparisons between Fig. 15.2 LED colour panel producing dynamic colour-changing
columns in different greyness groups should only be façade. Photographs: Arthur Lyons
made in respect of lightness. The framework has up to
eight columns of equal lightness in each greyness group designers who need to coordinate colour specification
commencing with the highest lightness. Thus any across a broad range of building products. A range of
colour is defined through the system by its three-part materials may be colour-referenced using the system;
code; for example, Magnolia is yellow-red 08, nearly these include wall, floor and ceiling tiles, carpets,
grey B and low-weight 15 (i.e. 08 B 15), Midnight 20 C fabrics, wall coverings, flexible floor finishes, paints,
40 and Plum 02 C 39. The standard BS 4800: 2011 gives architectural ironmongery and metalwork, sanitary
the approximate Munsell reference and detailed fittings, laminates and furniture.
reflectance data for each colour code.

NATURAL COLOUR SYSTEM

The Natural Colour System®© (NCS) was developed by
the Scandinavian Colour Institute, launched in 1978
and modified in 1995 with a second edition in which
extra colours were incorporated and some removed,
leaving a total of 1950 colours. It is a colour language
system which can describe any colour by a notation,
communicable in words without the need for visual
matching. It has been used by architects, builders and

PAINTS, WOOD STAINS, VARNISH, COLOUR 433

BS4800: 2011 Specification for paint colours for building purposes

Greyness

A group B group C group D group E group
grey nearly grey grey/clear nearly clear clear

Hue 01 01 03 05 07 09 11 13 15 17 19 21 23 25 29 31 33 35 37 39 40 41 42 43 44 45 46 49 50 51 53 55 56 57 58

02 red-purple Plum
02 C 39

04 red Tawny Poppy
04 D 44 04 E 53

06 yellow-red Mid tan Apricot
06 D 43 06 E 50

08 yellow-red Magnolia Butterscotch
10 yellow 08 B 15 08 C 35

Dawn grey Pale primrose
10 A 03 10 E 49

12 green-yellow Spruce green
12 B 25

14 green Moss green
14 C 40

16 blue-green Duck egg
16 C 33

18 blue Raven
18 B 29

20 purple-blue Midnight Cornflower
20 C 40 20 E 51

22 violet Pale lavender Purple heather
22 B 17 22 C 37

24 purple Pale lilac
00 neutral 24 C 33

Oyster grey Black
00 A 01 00 E 53

Fig. 15.3 British Standards Colour System with some illustrative examples

The Natural Colour System is based on the assump- vertical axis illustrating blackness/whiteness. A colour
tion that for people with normal vision there are six may therefore be described as having 10% blackness
pure colours: yellow, red, blue, green, white and and 80% chromatic intensity. The full colour specifi-
black. The four colours yellow, red, blue and green are cation thus reads NCS S 1080-Y50R for an orange
arranged around the colour circle, which is then sub- with 10% blackness, 80% chromatic intensity at yellow
divided into 10% steps. For example, yellow changes with 50% red. The S refers to the standardised NCS
to red through orange, which could be described as 1950 original colours.
Y50R (yellow with 50% red) (Fig. 15.4). In order to
superimpose the black/white variation and also inten- The system allows for a finer subdivision of the
sity of colour, each of the 40 10% steps around the colour circle, and this is necessary to define any colour
colour circle may be represented by colour triangles, and to make direct comparisons with colours defined
with the pure colour at the perimeter apex and the within the British Standards system. Thus Magnolia
(BS 08 B 15) is NCS 0606-Y41R (6% blackness,