Spray Foam Roof Insulation R Value

Install a spray foam roofing system.

Spray foam roof insulation r value.

However there are open cell spray foam insulation products actually offer r 3 7 per inch such as icynene classic and. 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. Most of the time spray foam can be directly applied to existing roofing systems but in some cases a polyiso board is needed. It has a lower r value per inch than closed cell foam and is vapor permeable.

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. Focusing on spray foam insulation materials there is a difference between the two main types. Closed cell spray foam insulation. Recommended home insulation r values.

A spray foam roofing system has an r value of 6 6 per sq. 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. 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.

For 6 inches r 15 or r 19 etc. Insulation level are specified by 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. 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 foams are between 5 and 1 lbs per cubic foot and have an r value of 3 0 4 0 per inch of insulation. 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. 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. The higher the r value the better the thermal performance of the insulation.

If you install 2 inches of iso board r 11 and 3 inches of spray foam r 19 8 you ll be over an. R value is a measure of insulation s ability to resist heat traveling through it. For example closed cell spray foam depending on brand can offer an r 6 or r 7 per inch. The table below shows what levels of insulation are cost effective for different climates and.

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. 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. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13.