Properly Detail Between Deck and House - Rutgers University

GREEN BUILDING MANUAL NEW RESIDENTIAL UPDATED 28-FEB-11

Properly Detail Between Deck and House

What is Proper Detailing Between Deck and House?

Properly detailing between a deck and the house is the process that prevents water from flowing
into and sitting in the ledger plate and rim joists of the house.1 The connections between the deck

and the house create areas for water to collect, and these points become vulnerable to moisture
problems.2 Moisture problems can have disastrous effects on structural integrity, so it is very

important to handle properly to protect detail these connections properly. Since decks are

outside and unprotected from the elements, it is important to take extra care with this task in
areas that are in especially wet climate areas or coastal regions.3

How to Implement
Proper Detailing
between Deck and
House

There are several basic
steps to ensure proper
detailing between the
deck and the house that
will help prevent
moisture problems.

Caulk pilot holes for
connection Add caulk to
the pilot holes in joists
before installing screws
to ensure that water does
not pool in the hole after
the fact.

Add spacers in pilot Figure 1 – Proper flashing between deck and house
(Source: US Forest Service – Forest Products Laboratory)
holes Adding spacers in
the pilot holes will allow

a gap that will aid in water drainage and drying.4

1 New Jersey Green Home Remodeling Guidelines Version 1.0, pg. 224, Rutgers Center for Green Building, 2009,

https://sakai.rutgers.edu/access/content/group/1905495c-8a4e-4cfa-9d4b-

355caf62856d/Projects/Green%20Building%20Manual/Resource%20Documents/NJGHRG_v1.0.pdf
2 Home Construction and Improvement, Expert Home Improvement Advice, Flashing a Deck Ledger Board

Properly, http://www.homeconstructionimprovement.com/how-to-properly-flash-deck-ledger-board/ (accessed

October 24, 2010).
3 Safe Strong Home, 5 Steps to a Safer, Stronger Deck, http://www.safestronghome.com/deck/04.asp (accessed

October 24, 2010).
4 Details for a Lasting Deck, Government Scientists Study Outdoor Structures and Report on which Details,

Fasteners, and Finishes Hold Up Best, Bob Falk and Sam Williams,

http://www.fpl.fs.fed.us/documents/pdf1997/falk97d.pdf (accessed October 24, 2010).

GREEN BUILDING MANUAL NEW RESIDENTIAL UPDATED 28-FEB-11

Leave gap for drainage between deck and house Leaving a gap between the first board of the
deck and the exterior wall of the house will allow water to drain, not pool.

Use the right connectors Stainless steel is the best choice for connector material, since it holds
up well in both wet and salty environments. It is also important to consider compatibility when
choosing connector materials. For example, lumber treated with copper is corrosive to steel.5

Flash properly Flashing is a thin layer of waterproof material that keeps water from going into
areas where it should not go.6 It prevents water from running into crevices in and around the
house, and instead directs it away from the house. When installed correctly, it should extend
under the siding above the deck and extend over the siding below the deck.7 There are many
kinds of flashing materials such as aluminum, copper, galvanized steel, and PVC.8 Flashing
cement ensures a tight seal. Finally, it is important to ensure that any fasteners used to secure
flashing are compatible in terms of their materials.9

Benefits

Resource conservation Proper detailing between decks and houses will result in fewer repairs
and replacements of the deck.10 Trapped water leads to decay, and therefore, an improperly
detailed deck and house will experience moisture related problems.11 A longer deck lifespan
means that less lumber and other timber products will be used over time. Therefore, fewer trees
will need to be cut down and processed for deck lumber.

Healthier indoor and outdoor environment By limiting areas where moisture can collect, you
limit the chance of mold and mildew growth. This protects the air from problems associated
with this kind of growth.

5 New Jersey Green Home Remodeling Guidelines Version 1.0, pg. 224, Rutgers Center for Green Building, 2009,

https://sakai.rutgers.edu/access/content/group/1905495c-8a4e-4cfa-9d4b-

355caf62856d/Projects/Green%20Building%20Manual/Resource%20Documents/NJGHRG_v1.0.pdf
6 Old House Web, Flashing – What it is and Why it is Important, http://www.oldhouseweb.com/how-to-

advice/flashing-what-it-is-and-why-is-it-important.shtml (accessed October 24, 2010).
7 Details for a Lasting Deck, Government Scientists Study Outdoor Structures and Report on which Details,

Fasteners, and Finishes Hold Up Best, Bob Falk and Sam Williams,

http://www.fpl.fs.fed.us/documents/pdf1997/falk97d.pdf (accessed October 24, 2010).
8 Old House Web, Flashing – What it is and Why it is Important, http://www.oldhouseweb.com/how-to-

advice/flashing-what-it-is-and-why-is-it-important.shtml (accessed October 24, 2010).
9 FEMA, Roof-to-Wall and Deck-to-Wall Flashing, Home Builders Guide to Coastal Construction, Technical Fact

Sheet No. 24, http://www.fema.gov%2flibrary%2ffile%3ftype%3dpublishedfile%26file%3dhgcc_fact24.pdf

(accessed October 24, 2010).
10 New Jersey Green Home Remodeling Guidelines Version 1.0, pg. 224, Rutgers Center for Green Building, 2009,

https://sakai.rutgers.edu/access/content/group/1905495c-8a4e-4cfa-9d4b-

355caf62856d/Projects/Green%20Building%20Manual/Resource%20Documents/NJGHRG_v1.0.pdf
11 Old House Web, Flashing – What it is and Why it is Important, http://www.oldhouseweb.com/how-to-

advice/flashing-what-it-is-and-why-is-it-important.shtml (accessed October 24, 2010).

GREEN BUILDING MANUAL NEW RESIDENTIAL UPDATED 28-FEB-11

Occupant safety Detailing the area between a deck and house ensures a stronger deck.
Therefore, the risk of deck failure is reduced. This lessens the chance for injury resulting from
the collapse of part of or the entire deck.

Cost

Having a properly detailed area between the deck and the house will save money over the course
of the deck lifespan. Reduced incidence of repair and replacement saves money since these
kinds of upfront costs are less frequent. Consider hiring a professional to detail between the deck
and the house.12 It may cost more initially, but having quality work done will result in longer-
lasting structures and less costs in repair and replacement later.

Resources

Home Construction and Improvement, Expert Home Improvement Advice, Flashing a Deck
Ledger Board Properly
http://www.homeconstructionimprovement.com/how-to-properly-flash-deck-ledger-board/

Safe Strong Home, 5 Steps to a Safer, Stronger Deck
http://www.safestronghome.com/deck/04.asp

Details for a Lasting Deck, Government Scientists Study Outdoor Structures and Report on
which Details, Fasteners, and Finishes Hold Up Best, Bob Falk and Sam Williams
http://www.fpl.fs.fed.us/documents/pdf1997/falk97d.pdf

FEMA, Roof-to-Wall and Deck-to-Wall Flashing, Home Builders Guide to Coastal
Construction, Technical Fact Sheet No. 24
http://www.fema.gov%2flibrary%2ffile%3ftype%3dpublishedfile%26file%3dhgcc_fact24.pdf

New Jersey Green Home Remodeling Guidelines Version 1.0, Rutgers Center for Green
Building, 2009
https://sakai.rutgers.edu/access/content/group/1905495c-8a4e-4cfa-9d4b-
355caf62856d/Projects/Green%20Building%20Manual/Resource%20Documents/NJGHRG_v1.
0.pdf

Old House Web, Flashing – What it is and Why it is Important
http://www.oldhouseweb.com/how-to-advice/flashing-what-it-is-and-why-is-it-important.shtml

12 New Jersey Green Home Remodeling Guidelines Version 1.0, pg. 224, Rutgers Center for Green Building, 2009,
https://sakai.rutgers.edu/access/content/group/1905495c-8a4e-4cfa-9d4b-
355caf62856d/Projects/Green%20Building%20Manual/Resource%20Documents/NJGHRG_v1.0.pdf