Open Cell Foam Insulation In Attic

The minimal layer applied to individual attic elements should have approx.

Open cell foam insulation in attic.

For bigger jobs such as roof attic floor and wall insulation you will need professional help and equipment. The myth that open cell is more economical is bullshit. This spray foam is applied as a low or high pressure two component polyurethane spray foam that can be applied onto walls in unvented attics to ducts and ceilings and in vented attics and crawl spaces. To be labeled as open cell foam more than half of the cells must be open which means the bubbles.

Do it right and your roof will not rot. Most insulation contractors are recommending open because it s cheaper and also because if i go with closed cell and the roof leaks it will not penetrate the insulation and could remain stuck between the sheathing and the insulation and could rot the wood and or travel to a more hidden spot of the roof or attic causing worse problems that are harder to notice than if the roof leaked and water penetrated through the open cell which i would be able to see and fix if necessary. When applied on the interior open cell spray insulation provides performance advantages that differ from those of closed cell spray foam used on the exterior. The evaluation service report esr for spray foam insulation products provides a valuable resource based on a third party review of testing information useful for utilizing these products successfully and according to code requirements.

Closed cell spray foam exterior applications. The open cell polyurethane foam has an r value of 3 5 to 3 6 per inch with a price tag of 1 1 20 square foot. Closed cell foam will act as a vapor barrier when installed to a depth of at least 2 while open cell foam won t act like a vapor barrier at any depth. Open cell foam has an insulation value of up to r 3 9 inch while closed cell has an insulation value of up to r 6 9 inch.

Both low density open cell and medium density closed cell spray foam can be used in an unvented attic to provide the needed thermal resistance and airtightness. Lstiburek says to do it for every spray foam attic. Open cell spray foam is a perfectly acceptable insulation product to use in attics. Open cell foam weighs 1 2 pound per cubic foot and closed cell weighs 2 lbs per cubic foot.

20 cm usually it s 18 cm. Architectural firms can specify both the building envelope for a total performance option. Others like david butler see his comment below say you need to do it only if a moisture problem develops. There you have it.

It is worth remembering the insulation thickness depends on many factors like design assumptions or the expected insulation efficiency. Open cell foam has an r value of about 3 5 to 3 7 per inch while closed cell foam has an. There is 300 difference there but the cost they give you is about a third difference and open cell foam at 12 inches will not give you the performance of 2 inches of closed. Insulating value and strength.

Open cell foam insulation in attics the basic difference.