Spray Foam Roof Insulation R Value

The higher the r value the better the thermal performance of the insulation.

Spray foam roof insulation r value.

Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value. Focusing on spray foam insulation materials there is a difference between the two main types. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. The table below shows what levels of insulation are cost effective for different climates and.

Most of the time spray foam can be directly applied to existing roofing systems but in some cases a polyiso board is needed. 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. 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.

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. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. A typical 2 4 stud filled with open cell spray foam will have an r value. R value is a measure of insulation s ability to resist heat traveling through it.

For 6 inches r 15 or r 19 etc. Insulation level are specified by r value. For example closed cell spray foam depending on brand can offer an r 6 or r 7 per inch. A spray foam roofing system has an r value of 6 6 per sq.

If you install 2 inches of iso board r 11 and 3 inches of spray foam r 19 8 you ll be over an. However there are open cell spray foam insulation products actually offer r 3 7 per inch such as icynene classic and. Recommended home insulation r values. Install a spray foam roofing system.

Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. 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. 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. 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.

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 r values. Closed cell spray foam insulation.