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Cellulose Insulation Manufacturers Association

Determining Current Home Attic Insulation R-Value

When trying to determine your current R-Value in the attic, use a ruler to measure the depth of the insulation and multiply the depth by the R-Value of the material.

For example, and attic with 6 inches of Modern insulation would have an estimated R-Value of 22.5 (6 inches x 3.75 R-Value per inch)

Unless you still have the packaging for the insulation used in the attic, it will be hard to measure the exact R-Value of the installed product. To calculate the R-Value use the following guidelines for estimation purposes only:

R-Value / Inch
Blown-in Cellulose 3.75
Blown-in Fiberglass 2.7
Fiberglass Batts 3.7
Cotton Batts 3.7
Open-cell Foam 3.6
Close-cell Foam 5.8

Learn about how to determine current insulation in this post on the Greenest Insulation Blog. Remember, cellulose insulation can be blown on top of existing insulation to improve R-Values without removing the already installed insulation.

Contact a CIMA Producer in your state for referrals on energy auditors and professional insulation contractors.