Closed Cell Spray Foam With 1 5 Mineral Wool In Attic

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.

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

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. Mineral stone wool insulation batts are slightly better insulators than the off the shelf fiberglass batts sold at most lumberyards and home centers. 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. Mineral wool batts for 2 4 walls have an r value of 15 while a standard fiberglass batt made to fit in a 2 4 wall has an r value of 11 or 13.

In this case you have a choice of several prescriptive materials approved by the code as ignition barriers. Most ceilings are made of 1 2 drywall. Oregon shepard add boric acid sodium pentaborate dehydrate and a proprietary component that includes a natural protein last i checked with them. 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. Two types of spray foam insulation exist namely open cell and closed cell. 1 5 mineral fiber insulation. 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.

First spray foam has the best stc rating of all the options. Open cell spray foam r values. Why open cell oc spray foam is best for sound attenuation. The foam must be thick enough to meet minimum code requirements.

Closed cell spray foam uses blowing agents with a high global warming potential and open cell spray foam needs a carefully detailed vapor barrier to prevent moisture accumulation in the sheathing. It can be used between wood framed walls and in the attic floor. In this case the typical expense of spray foam insulation installation is 2 128. Top brands of wool insulation.

In these humid attics the moisture is getting through the open cell spray foam by vapor diffusion not via air leakage. It ties with rock wool batts for an stc of 50 in a laboratory test environment. 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. Black mountain natuwool which is 95 wool with 5 polyester binder and is treated with borax.

The main drawback is high cost.