Spray Foam R Value Thickness

Closed cell spray foam r values.

Spray foam r value thickness.

In the case of spray foam roofing the goal is to maximize r. Of thickness today tomorrow and 10 years from now. 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. For example blown fiberglass typically has an r value of only r 2 to r 3 per inch depending on compression density and moisture.

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. A typical 2 4 stud filled with open cell spray foam will have an r value between 10 5 and 14. Spray foam s r value does not decrease over time. R value is the term given to thermal resistance to heat flow.

The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. 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. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. Spray polyurethane foam will have an r value of 6 6 per sq.

The higher the r value of an insulation product the more effective the insulation properties. Hopefully today you learned that more isn t better in every situation. It has a lower r value per inch than closed cell foam and is vapor permeable. Blown in or loose fill insulation insulation blankets batts and rolls spray foam insulation and foam board insulation.

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. Closed cell spray foam insulation. 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. For 6 inches r 15 or r 19 etc.

Note that the material the insulation is made from will change the r value as well. As a benchmark one inch of solid wood has an r value of 1. 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.