Closed Cell Vs Open Cell Foam In Attic

To support traffic and loads better.

Closed cell vs open cell foam in attic.

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. Id go with closed cell. Closed cell foam for insulation applications range in density from 1 7 lb cu. Closed cell foam has a higher r value than open cell foam usually about 6 0 per inch.

Closed cell foam can be over three times that with a density of 1 75 pounds per cubic foot or more. Closed cell foam is much denser than open cell foam. Open cell spray foam insulation needs to be at full thickness before it can act as an air barrier. A lot of builders and homeowners are going with spray foam insulation because of the airtightness benefits.

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. A foams r value is its resistance to heat flow or in other words how well they insulate. Closed cell foam differs in that all of its tiny foam cells are closed and packed together. 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.

Open cell is more susceptible to mold and mildew but its expanding so it can hermetically seal an area. Closed cell is denser better insulating. It is either open cell foam where the tiny cells of the foam are not completely closed. But then the questioner mentioned that the spray foam contractor had intentionally left big holes to the outside by not sealing the gable vents.

This makes the foam weaker or softer feeling than closed cell foam. They are broken and air fills all of the open space inside the material. Closed cell foam can also increase the racking strength of attic walls which. Roofing applications typically use a 2 8 to 3 0 lb cu.

An overview of closed cell spray foam insulation closed cell spray foam insulation is highly efficient. Seems like you wouldnt want to seal something susceptible to mold growth but maybe thats just me. Most open cell foam has a density of about 5 pounds per cubic foot. Open cell foams typically weigh in at 0 4 to 0 5 lb cu.