Attic Insulation R Values Inches

As a benchmark one inch of solid wood has an r value of 1.

Attic insulation r values inches.

Depth inches total insulation r value. Small gray flat pieces or fibers from newsprint cellulose 3 7 x depth. As you can see there s some variation in r value depending on the particular type and brand of products used. 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.

The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. Fiberglass 2 5 x depth. Click the button to calculate the approximate r value for this job. 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.

Rock wool 2 8 x depth. Input depth of existing blown in insulation in inches. Dense gray or near white may have black specs. Vermiculite or perlite 2 7 x depth.

You can achieve better thermal performance in your attic by adding an additional layer of insulation. This calculator is to be used as an estimating tool only. Light weight yellow pink or white. Batts light weight yellow pink or white.

R value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another. It has a lower r value per inch than closed cell foam and is vapor permeable. The higher the r value the better the thermal performance of the insulation. Achieving greater r values in exterior walls.