Spray Foam Roof Insulation R Value

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.

Spray foam roof insulation r value.

A typical 2 4 stud filled with open cell spray foam will have an r value. The higher the r value the better the thermal performance of the insulation. Phenolic foam spray insulation. Focusing on spray foam insulation materials there is a difference between the two main types.

R 0 77 30 phenolic foam insulation r values. 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. It has a lower r value per inch than closed cell foam and is vapor permeable. Closed cell foam can also add to the structural strength of the roof system which can make it a more appealing choice in locations that frequently endure high winds.

Corrosion problems when in contact with steel roofing moisture. 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. 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. Closed cell spray foam insulation.

R value is a measure of insulation s ability to resist heat traveling through it. Insulation level are specified by r value. 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. For 6 inches r 15 or r 19 etc.

8 3 4 4 8 2 20. Recommended home insulation r values. R values are additive so you can multiple the number of inches of insulation thickness times the r value to arrive at a total insulation value. However there are open cell spray foam insulation products actually offer r 3 7 per inch such as icynene classic and.

The table below shows what levels of insulation are cost effective for different climates and. 4 8 7 21. 4 5 21. 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.

Having an r value in the neighborhood of r 7 per inch and the ability for some products to be applied 5 inches at once high r value applications are easily achieved. 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. For example closed cell spray foam depending on brand can offer an r 6 or r 7 per inch. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.

For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13.