Closed Cell Spray Foam With 1 5 Mineral Wool In Attic

Why open cell oc spray foam is best for sound attenuation.

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

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. 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. 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.

Spray foam with air. 1 5 mineral fiber insulation. 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. In these humid attics the moisture is getting through the open cell spray foam by vapor diffusion not via air leakage.

First spray foam has the best stc rating of all the options. Black mountain natuwool which is 95 wool with 5 polyester binder and is treated with borax. In this case the typical expense of spray foam insulation installation is 2 128. Top brands of wool insulation.

However in real construction a batt would be cut to fit around utilities and boxes leaving sound transfer cracks. 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. The main drawback is high cost.

But the spray foam is still exposed to the attic and needs an ignition barrier. Two types of spray foam insulation exist namely open cell and closed cell. 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. 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.

Oregon shepard add boric acid sodium pentaborate dehydrate and a proprietary component that includes a natural protein last i checked with them. The foam must be thick enough to meet minimum code requirements. 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. 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.

Mineral stone wool insulation batts are slightly better insulators than the off the shelf fiberglass batts sold at most lumberyards and home centers.