ceiling

CEILING FINISHES
PLASTER

1. Type Selection
Plaster

Plaster is a building material used for coating walls and ceilings. It is
manufactured by dry powder and is mix with water to form a paste when used.
The reaction with water liberates heat through crystallization and the hydrated
plaster then hardens. Plaster can be relatively easily worked with metals tools or
even sandpaper. These characteristic make plaster suitable for a finishing, rather
than the load bearing material.

2. Advantages and disadvantages

Advantages

 Easier mode to add permanent design without experimenting with any
undependable or difficult painting technique.

 Have plenty of choices for creating designs and styles with plasters
 Great decorative appeal(can decorate your interior with different designs
 Strong and more durables then others
 Dust not produce dust as the dry wall does

Disadvantages

 Difficult of repairing the damaged
 With time, plaster can change its colour and need to be renovated
 Cost higher (services need to be renovated or repainted only specialized

labour)

3. Installation

Figure 1 : Covering the ceiling

I. Cover the ceiling with oriented strand board fastened to ceiling joists with a
hammer and galvanized nails. Staple a waterproof membrane such as
polystyrene over the OSB with a construction stapler and nail metal wire mesh
lath on top of the membrane, as tightly as possible.

Figure 2 : Plaster mixing and Scratch Coat

II. Mix plaster in a large container; use a type called "scratch coat" and mix it so it
spreads easily but will stand on its own. The consistency is important. Test it by
putting a bit on one corner of the lath to make sure it holds. Spread it over the
lath with a flat mason's trowel, scooping up plaster with the end of the trowel
and spreading it with the flat bottom, about 3/8-inch thick. Scrape or "scratch" it
with the notched side of the trowel as it begins to set.

Figure 3 : Scratch coat cure fully

III. Let the scratch coat cure fully, normally at least 48 hours, keeping it slightly
moist with a misting sprayer while it cures. Mix a batch of "brown coat" plaster,
with some fine sand in it, and spread it on top of the scratch coat, about 1/4-inch
thick. Smooth it with the flat edge of the trowel. Let that coat cure at least 24
hours, misting it to keep it slightly damp.

Figure 4 : Design the ceiling

IV. Add a finish coat, using a plaster designated for finishing, with the flat trowel.
Spread this thinner, 1/8 to 1/4-inch thick and smooth it with the straight edge of
the trowel. Put any texture or design into the finish coat. Make swirls with the
notched edge or put the flat bottom on the plaster and pull it up slightly, then
smooth the peaks of the material that was pulled up to create a traditional
plaster look.

4. Factor need to be consider

Figure 5 : Aesthetic Expectations

I. Aesthetic Expectations: Ceiling finish materials, heights, and profiles can create
inviting environments and can influence the way light interacts with the building
interior. Unlike floors, ceilings are not limited to a single horizontal plane; they
can be articulated at several elevations or can include vertical or sloped surfaces.
Ceilings are used to introduce a sense of scale and proportion to an interior
space. For example, if the area of the room is large, a high ceiling can create a
grand space; however, if the area is small and the ceiling is high, the room may
simply feel cavernous.

Figure 6 : mechanical and electrical equipment

II. Conceal the Building Utilities Overhead (mechanical and electrical equipment
and components): The most common reason for a ceiling is to conceal the
building structure and overhead utilities, and the choice of materials should be
carefully accounted for.

Figure 7 : Wind Loading

III. Wind Loading: Wind can impose an uplift load on the exterior soffit surface;
therefore, wind-uplift resistance becomes an important consideration. In
circumstances when large areas of the building enclosure are regularly opened
to the exterior, wind can enter the building and exert a force on the ceilings.

Figure 8 : Moisture absorption

IV. Humidity: Ceilings adjacent to openings in exterior walls, especially major
openings such as at a bank of frequently used doors, may be subjected to higher
levels of humidity than the ceilings in the remainder of the building. Because
many materials, when oriented horizontally, are vulnerable to sagging due to
moisture absorption, the choice of materials must be carefully considered.

Figure 9 : Cause of fire

V. Flammability: Building codes sometimes require ceilings to be resistant to fire
propagation and spread. Fire rated materials should be used to give ample time
for occupants to vacate the building.

VI. Seismic: In seismically active areas, building codes require products, materials,
and equipment installed overhead to resist the movements caused by an
earthquake. During seismic activity, support structures and ceiling finish
materials must not fall down, which would cause injuries to people trying to
vacate the building.

VII. Sound Absorption: Ceiling finish materials and the method of application can
help absorb sound generated within a room or space.

VIII. Sound Isolation: Building codes sometimes require that a floor/ceiling assembly
help isolate sound from above. Hence reducing the rate of sound interference
among the building users.

IX. Sustainability: Many ceiling products contain recycled content and are energy
efficient, which can make positive contributions to sustainability goals.
Sustainable materials are chosen keeping in mind various characteristics like
zero or low toxicity, zero or low off gassing of harmful air emissions and
durability.

X. Antimicrobial Resistance: In addition to normal maintenance, some applications
may require ceilings to be resistant to bacteria growth and mold and mildew
development, especially in health centers, hospitals and high end kitchens.

Figure 10 : Light Reflected

XI. Light Reflectance: Ceilings can be used to reflect and/or diffuse light from other
sources in order to uniformly distribute it throughout a space. Sometimes certain
ceiling finish materials are selected specifically to give the space a brighter
appearance because indirect lighting is the preferred lighting source. This is also
an important consideration when day-lighting an interior space is part of the
design.

XII. Maintenance: Some occupancy, such as health care facilities and hospitals,
require ceiling finishes that can be regularly cleaned and scrubbed to remove
possible contaminates. Other occupancies may require ceilings to resist soiling,
scratching, and impact

Figure 11 : Ceiling Finishing