Attic Insulation R Values Inches

Input depth of existing blown in insulation in inches.

Attic insulation r values inches.

Fiberglass 2 5 x depth. R value of insulation by type. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. Rock wool 2 8 x depth.

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. Vermiculite or perlite 2 7 x depth. Batts light weight yellow pink or white. Small gray flat pieces or fibers from newsprint cellulose 3 7 x depth.

You can achieve better thermal performance in your attic by adding an additional layer of insulation. Click the button to calculate the approximate r value for this job. As you can see there s some variation in r value depending on the particular type and brand of products used. This calculator is to be used as an estimating tool only.

Depth inches total insulation r value. The higher the r value the better the thermal performance of the insulation. Closed cell spray foam insulation. Dense gray or near white may have black specs.

Here are the r values per inch of the most common types of insulation. As a benchmark one inch of solid wood has an r value of 1. 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. Light weight yellow pink or white.