Fiberglass Batts Labeled vs Installed Performance

"Perfectly installed” batts lose 11% of their labeled R-Value, "commonly installed” fiberglass batts lose 28% of their labeled R-value

Monday, October 30, 2017

Insullation Effictiveness Bulletin

This study confirms tests conducted 20 years ago by fiberglass manufacturers, and reveals the surprisingly large disparity between the labeled R-value and the installed R-value of fiberglass batts.

Summary of the Test:

Oak Ridge National Laboratory research shows that “perfectly installed” batts lose 11% of their labeled R-Value, and that “commonly installed” fiberglass batts lose 28% of their labeled R-value. This study confirms tests conducted 20 years ago by fiberglass manufacturers, and reveals the surprisingly large disparity between the labeled R-value and the installed R-value of fiberglass batts.

The study was performed by Oak Ridge National Labratory out of Oak Ridge, TN.

What was measured?

The R-value results presented here are the clear wall R-values, which Andre Desjarlais of Oak Ridge explains, “includes the studs, top and bottom plates, sheathings and exterior façade… It does not include additional structural components around details such as corners, windows, etc.

“The clear wall R-value… represents the area of the wall containing insulation and only the necessary structural member away from all interface details.”

What did the test find?

The highest tested R-value for “R-19” labeled batts was R-17.4 for batts before they were installed. From there, the test results dropped to R-17 and then R-13.7.

Download Fiberglass
Labeled vs Installed Performance

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