House Construction With Foam Barrier Instead of Wood

Framing

• Wooden sheathing reinforces the frame of your home against the force of wind pushing laterally against it. An external sheath made from foam does not provide adequate bracing against the force of the wind. Installing diagonal wooden braces in the wooden or metal frame of your home will safely redirect the force of the wind toward your foundation, protecting your home from damage during high winds.

Fastening

• Foam barriers are not strong enough to support siding or fixtures that are only fastened to the foam. You must attach any fixtures such as siding or heavy exterior lighting that you install on the outside of your exterior walls directly to the studs of your home. Since the minimum thickness of foam barriers is 1/2 inch, any siding you install will need longer fasteners so they can penetrate both the foam barrier and the studs behind it.

Moisture

• Foam barriers need a continuous weather barrier to prevent moisture from penetrating your home. Seal every joint between the foam panels with tape and install flashing around the edges of windows and doors to ensure that the panels provide a continuous barrier against moisture penetration. In warm southern climates you should always install impermeable foam to prevent the warm, moist air from penetrating your home. In colder northern climates, installing a foam barrier using panels with a perm rating of 1 or 2 per inch of thickness will allow moist air from the interior of your home that has condensed inside your walls to escape.

Insects

• Foam panels provide a potential haven for carpenter ants and a potential path for termites to reach the wooden framing of your home. If you live in a warm climate where termites are common, leaving a gap of at least 6 inches between the ground and the foam paneling in your walls helps prevent infestations and makes identifying their location easier.

Benefits

• Foam panels are less expensive than wood and are easier to cut and work with. Foam barriers create an additional insulating barrier in your home that will increase the energy efficiency of your home. Wood sheathing is rated to reduce heat flow with an average R-value of 0.6 for 1/2 inch of plywood. Foam barrier products of the same thickness have R-values of between 2 and 3.6, depending on the type of foam used.