Closed Cell Vs Open Cell Foam In Attic

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 vs open cell foam in attic.

It is either open cell foam where the tiny cells of the foam are not completely closed. Open cell spray foam insulation needs to be at full thickness before it can act as an air barrier. Open cell is more susceptible to mold and mildew but its expanding so it can hermetically seal an area. Closed cell foam is much denser than open cell foam.

Open cell foams typically weigh in at 0 4 to 0 5 lb cu. A foams r value is its resistance to heat flow or in other words how well they insulate. They are broken and air fills all of the open space inside the material. An overview of closed cell spray foam insulation closed cell spray foam insulation is highly efficient.

Closed cell spray foam insulation acts as an air barrier at any thickness due to its solid properties. But then the questioner mentioned that the spray foam contractor had intentionally left big holes to the outside by not sealing the gable vents. Roofing applications typically use a 2 8 to 3 0 lb cu. Closed cell is denser better insulating.

Id go with closed cell. Seems like you wouldnt want to seal something susceptible to mold growth but maybe thats just me. Closed cell foam differs in that all of its tiny foam cells are closed and packed together. Most open cell foam has a density of about 5 pounds per cubic foot.

As a result in iecc climate zones 5 and higher building codes require the use of a vapor retarder if you install open cell spray foam. Closed cell foam can also increase the racking strength of attic walls which. If you need an air barrier as part of your installation closed cell is a better choice. 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.

Closed cell foam for insulation applications range in density from 1 7 lb cu. Closed cell foam can be over three times that with a density of 1 75 pounds per cubic foot or more. Open cell foam is used in a wide range of applications such as for noise reduction in sound rooms home insulation metal buildings under roof deck for semi conditioned attics and more. Closed cell foam has a higher r value than open cell foam usually about 6 0 per inch.