Spray Foam Insulation Thickness R Value

R value is a measure of insulation s ability to resist heat traveling through it.

Spray foam insulation thickness 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. 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. The table below shows what levels of insulation are cost effective for different climates and. 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 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. Insulation level are specified by r value. As a benchmark one inch of solid wood has an r value of 1. Closed cell spray foam r values.

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. 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 common denominator among varieties of insulation is the r value. 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. All these have r values ranging from r 3 2 to r 3 8 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 closed cell spray foam depending on brand can offer an r 6 or r 7 per inch.

Recommended home insulation r values. Open cell foam insulation values r3 r4. In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and. 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.

Closed cell spray foam insulation. When calculating the r value of a multilayered installation add the r values of the individual layers. The r value depends on the type of insulation its thickness and its density. For 6 inches r 15 or r 19 etc.

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. The higher the r value the better the thermal performance of the insulation. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13.