Spray Foam Insulation R Value

Traditional insulation such as cellulose or fiberglass is not comparable to spray foam insulation in r value as those insulation methods use r value of heat transfer.

Spray foam insulation r value.

Closed cell spray foam has a far better r value per inch than other less effective insulations like cellulose fiberglass or even open cell foam. Bulky materials resist conductive and to a lesser degree convective heat flow in a building cavity. For 6 inches r 15 or r 19 etc. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13.

Since closed cell foam has a higher r value per inch installers generally spray 2 in walls and 3 in rooflines to meet the energy code requirements of r 13 and r 19 respectively. The r value of spray foam insulation is approximately 6 per inch so those using spray foam as their insulator will need about 6 3 inches of thickness to reach r 38. Open cell spray foams are between 5 and 1 lbs per cubic foot and have an r value of 3 0 4 0 per inch of insulation. The r value of fiberglass insulation is approximately 2 2 per inch so much thicker fiberglass insulation is required to achieve the same r value of 38.

Closed cell spray foam insulation. Open cell spray foam has an r value of about r 3 7 per inch while closed cell spray foam has an r value that may be as high as r 6 5 per inch. I m not going to dive into the energy code here but these numbers apply to many climate zones the latter being allowed under the ua tradeoffs rule. According to industry publication fine home building the r value for open cell spray foam is between r 3 5 r 3 6 per inch.

Open cell spray foam insulation is air impermeable and is applied with a minimum of 3 5 on average and can be used for attics interior floors walls and soundproofing. It has a lower r value per inch than closed cell foam and is vapor permeable. Rigid foam boards trap air or another gas to resist conductive heat flow. Open cell foam insulation values r3 r4.

Closed cell spray foam r values. Why spray foam insulation is so effective in meeting code requirements is that it has a higher r value per inch of product used than batts. However there are open cell spray foam insulation products actually offer r 3 7 per inch such as icynene classic and. Focusing on spray foam insulation materials there is a difference between the two main types.

If you want to install spray foam in a stud wall and price is no object then it would seem to make sense to specify closed cell spray foam right.