Foam Board Insulation Tips

yellow wall insulation
  • 2-3 hours
  • Beginner
  • $20-70
What You'll Need
2x2 lumber
2x3 lumber
Fine toothed saw or craft knife
What You'll Need
2x2 lumber
2x3 lumber
Fine toothed saw or craft knife

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 consumption of non-renewable resources.

There are number of ways you can add extra insulation to your home, including fiberglass batting and spray cellulose or foam. Provided you have access and adequate workspace, foam board insulation may be the most effective insulation you can choose.

Foam board insulation is a great option because it not only provides high R-values, but it is also lightweight, 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.

Molded Expanded Polystyrene (MEPS) Boards

This is the same type of closed cell foam that is used to make things like coffee cups and cooler chests. The R-value depends on the thickness of the board, but it generally ranges from 3.8 to 4.4 per inch.

MEPS is the least expensive form of foam board insulation. It's relatively easy to install, but it's easy to damage, absorbs water vapor, and warps 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 and a more consistent density. It's firmer and makes an excellent choice for use in applications such as interior basement walls.

Urethanes: Polyurethane and Polyisocyanates

Both of these have high thermal resistance. The rigid cell structure of the foam makes it quite solid. It's often used in laminated panels along with a range of different facings such as plywood, metal, plastic, and paper.

Installing Foam Board Insulation

Foam board insulation can be applied directly onto concrete walls using a construction adhesive to hold it in place. Because foam board insulation is flammable, building codes require it to be covered with fire resistant paneling or drywall.

The best way to install foam board insulation under drywall is to frame the wall with 2x3-inch lumber for the top and bottom plates and 2x2-inch lumber for the studs. Cut your foam insulation panels to fit between the furring strips.

Cutting Foam Board Insulation

A popular option is to use a fine toothed hand saw. The fine teeth will create a fine foam dust that can be vacuumed. You can also use a craft knife by scoring a line with the tip of the blade. Then extend the blade out and make a second cut which slices the rest of the board.

A Couple of Tips

Don't leave your foam board insulation in the sun prior to installation. Direct sunlight will reduce the R-value of the insulation. All foam boards will absorb water vapor. Cover the insulation with a moisture/vapor barrier before you install your or paneling.