Closed Cell Attic Foam

Many builders in cold climates use closed cell spray foam instead because of its lower water vapor permeability which means it doesn t need the extra step of installing a vapor retarder.

Closed cell attic foam.

Closed cell foam can also increase the racking strength of attic walls which. But some closed cell foams like tiger foam s e84 closed cell formula have even higher ratings that go up to almost 7 per inch. In a vented attic all of that expensive airflow is lost to the environment. We are going to address the idea of air exchange in closed attics that use open cell foam.

The problem that can occur in a closed attic assembly is the management of the moisture that rises and accumulates in the attic space. Open cell foam weighs 1 2 pound per cubic foot and closed cell weighs 2 lbs per cubic foot. I have open cell in my house since 2004 and i would not use it in a dogs out house. This is very important in situations where your code requires an r 21 for the wall but you only have a 2 4 stud because closed cell spray foam is the only way you would achieve the required r value to meet code.

You see hot moist air rises the peak of the attic is the highest point and vapor drive moves from warm to cold. Closed cell foam can be over three times that with a density of 1 75 pounds per cubic foot or more. This type of spray foam offers the specific benefits of continuous insulation interior wall cavity fill and unvented attic applications. Closed cell foam can also add to the structural strength of the roof system which can make it a more appealing choice in locations that frequently endure high winds.

Closed cell closed cell is a two component medium density one to one by volume spray applied polyurethane foam. Intumescent coatings are not always needed to coat spray foam in the attic in order to meet code thermal barrier requirements. This medium density spray foam is a closed cell spray foam that is typically used where there is the need for r value insulation per inch possible. To produce closed cell requires the use of an a component iso and a blended b component resin which contains zero ozone depleting blowing agents catalysts polyols and fire retarding materials.

A foams r value is its resistance to heat flow or in other words how well they insulate. But open cell spray foam with a vapor retarder can work too. One huge benefit of the spray foam insulated attic is that conditioned air leakage from the ac furnace duct system is contained and used to condition the attic. That means if you used foam it green closed cell which is r 7 per inch it s r value for a 3 5 deep wall cavity would be r 24 5.

Open cell foam has an r value of about 3 5 to 3 7 per inch while closed cell foam has an r value of about 6 per inch.