Closed Cell Spray Foam With 1 5 Mineral Wool In Attic

In these humid attics the moisture is getting through the open cell spray foam by vapor diffusion not via air leakage.

Closed cell spray foam with 1 5 mineral wool in attic.

But the spray foam is still exposed to the attic and needs an ignition barrier. Spray foam insulation is available in open cell and closed cell. Why open cell oc spray foam is best for sound attenuation. Two types of spray foam insulation exist namely open cell and closed cell.

Mineral stone wool insulation batts are slightly better insulators than the off the shelf fiberglass batts sold at most lumberyards and home centers. Top brands of wool insulation. Open cell spray foam has a low density and is many times applied in interior walls and areas that are hard to reach in a home. Open cell spray foam r values.

As i noted in a different article air leakage through spray polyurethane foam open cell spray foam only needs to be 3 or 3 5 inches thick to form a decent air barrier. However in real construction a batt would be cut to fit around utilities and boxes leaving sound transfer cracks. Open cell spray foam typically has an r value of 3 5 per inch and it should be noted that open cell does not form a tight air seal. In this case the typical expense of spray foam insulation installation is 2 128.

Oregon shepard add boric acid sodium pentaborate dehydrate and a proprietary component that includes a natural protein last i checked with them. 1 5 mineral fiber insulation. It ties with rock wool batts for an stc of 50 in a laboratory test environment. The main drawback is high cost.

Most ceilings are made of 1 2 drywall. Spray foam with air. Open cell spray foam costs typically 0 25 to 0 50 per board foot and closed cell spray foam ranges from 0 90 to 1 50 per board foot. In this case you have a choice of several prescriptive materials approved by the code as ignition barriers.

The r value of open cell spray foam is about 3 5 per inch although the r value can be different depending on the product. It performs much better than any form of batt for stopping air flow but it is not as complete of an air seal as closed cell spray foam. It can be used between wood framed walls and in the attic floor. The foam must be thick enough to meet minimum code requirements.

First spray foam has the best stc rating of all the options.