Installing Foam Board Insulation

Adding insulation to your home is the kind of project we all like. It's a tremendous way to save some money while at the same time, helping the environment by minimizing your use of non-renewable resources. There's a number of ways you can add extra insulation to your home, including fiberglass bats and spray cellulose or foam, but provided you have access and room to work, foam board insulation may be the most effective insulation you can choose.

Foam board insulation is a great option for home insulation, because it not only provides high R-values (from R-4 up to R-8 per inch of thickness - almost 3 times the insulation value of fiberglass), but it's light in weight, easy to work with and can be used in virtually any location in your home. Here's some information about choosing and installing foam board insulation.

A quick primer of different types of foam board insulation

MEPS (Molded Expanded Polystyrene) boards

• This is the same type of closed cell foam that is used to make things like coffee cups or cooler chests. The R-value depends on how the thickness of the board but it generally ranges from 3.8 to 4.4 per inch.
• MEPS (or bead board) is the lest expensive form of foam board insulation and it’s relatively easy to install, but, its relatively easy to damage, absorbs water vapor and warps and chips easily.

Extruded Expanded Polystyrene (XEPS) Boards

• XEPS is a closed cell foam insulation, similar in structure to MEPS, but with a higher R value per inch (R-5) and a more consistent density, making it more firm and a good choice for use in applications such as interior basement walls.

Urethanes: Polyurethane and Polyisocyanates

• Both of these have high thermal resistance (between R-7 and R-8 per inch).
• The rigid cell structure of this foam makes it quite solid and its often used in laminated panels along with a range of different facings like plywood, metal, plastic or paper.

Installing Foam Board Insulation

• Foam board insulation can be applied directly onto concrete walls using a construction adhesive to hold it in place.
• However, because foam board insulation is flammable, building codes require it be covered with fire resistant paneling or drywall.
• The best way to install foam board insulation and allow it to be covered with drywall, is to  'fur out' or frame the wall using 2 X 3's for the top and bottom plates and 2 x 2's for the studs, spaced 24” apart.
• Cut your foam insulation (it usually comes in 4' X 8 sheets) into panels to fit between the furring strips.

Cutting Foam Board Insulation

• One option is to use a fine toothed handsaw such as a hacksaw. The fine teeth will create a fine foam 'dust ' that can be relatively easily vacuumed up.
• Alternatively, you could use a craft knife (Xacto knife). First score a line using the tip of the blade. Then extend the blade out (longer than the insulation is thick), and make a second cut the rest of the way through the board.

A Couple of Tips

• Don’t leave your foam board insulation sitting in the sun prior to installation. Direct sun will reduce the R-value of the insulation.
• All foam boards will absorb water vapor. Be sure to cover the insulation with a moisture/vapor barrier before you install your drywall or paneling.

Murray Anderson is an experienced freelance writer over 500 articles published on the web as well as in print magazines and newspapers in both the United States and Canada. He writes on a wide range of topics and is a regular contributor to DoItYourself.com. He can be contacted at murand@lycos.com.