Spray Foam R Value Thickness

In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and an inch of blown cellulose in an attic has an r value of 3 2 3 7.

Spray foam r value thickness.

Note that the material the insulation is made from will change the r value as well. For example blown fiberglass typically has an r value of only r 2 to r 3 per inch depending on compression density and moisture. The higher the r value of an insulation product the more effective the insulation properties. As a benchmark one inch of solid wood has an r value of 1.

The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. Insulstar spray foam insulation is a spray applied semi rigid cellular polyurethane foam plastic insulation having a maximum thickness of 2 inches and a nominal density of 2 0 pcf insulstar has an r value of 5 77 per inch so the maximum thickness of 2 inches yields an r value of about 11 5. In the case of spray foam roofing the goal is to maximize r. 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.

Of thickness today tomorrow and 10 years from now. Blown in or loose fill insulation insulation blankets batts and rolls spray foam insulation and foam board insulation. For 6 inches r 15 or r 19 etc. More spray foam isn t always better.

Closed cell spray foam insulation. Closed cell spray foam r values. Hopefully today you learned that more isn t better in every situation. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system.

Here are the installation methods from lowest to highest average r value per inch. 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 s r value does not decrease over time. When using this spray foam insulation cost calculator it is generally a good idea to factor in about 10 extra spray foam insulation cost to account for over spray waste and yield variations due to your particular ambient conditions.

R value is the term given to thermal resistance to heat flow. Depending on how close your calculated requirements are to the actual yield of the recommended kit size or quantity you may need more material to. 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. For example closed cell spray foam depending on brand can offer an r 6 or r 7 per inch.