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Insulation Products' Performance Depends on Proper Installation—Research Findings


Insulation Products' Performance Depends on Proper Installation—Research Findings

All insulation products—including fiberglass batts and spray foams—perform well when properly installed

By Mike Chamernik, Associate Editor September 4, 2015
Insulation_spray foam_installation
Installation is key when it comes to effective performance of insulation in home construction. (Photo: Flickr user dunktanktechnician)
This article first appeared in the PB September 2015 issue of Pro Builder.

All insulation products perform equally well when properly installed and air sealed, according to the Ther­mal Met­ric Sum­­­­mary Re­port, a stu­dy from Build­ing Science Cor­p. (BSC).

The final portion of the study, released in June 2015, tested the performance of various insulation materials—including fiberglass batts, closed-cell spray foam, and open-cell spray foam—in separate walls in clean, dry spaces with seasoned wood, over a range of temperatures from 144°F to –18°F.

The study found that when walls have the same R-value and are properly sealed, all insulation basically performs the same. When air sealing is not done properly and there is thermal bridging, the thermal bridging results in about a 15 percent decrease in thermal performance in all of the tested insulations, while R-value varies with temperature.


Few Surprises for Report Authors


These results aren’t surprising to Aaron Grin, a senior associate with BSC and one of the primary authors of the report. The study confirms what his group already knew. “When you’re dealing with the exact same framing layout,” Grin said, “we had a pretty good idea of how things would come out.”

Insulation manufacturers drew their own conclusions. The North American Insulation Manufacturers Association released a report stating that, while equally effective, fiberglass batts are cheaper than foam: To insulate and seal a 2,300 square foot house in climate zone 4 to IECC 2012 specifications, fiberglass batts would cost $4,600, compared with open-cell ($10,350) and closed-cell spray foam ($17,250).

Foam backers, such as the Spray Foam Coalition, say that their products are more versatile—foam fills gaps better and is easier to install in attics and crawlspaces. Builders will always have their own preferences among foam, fiberglass, and other materials. “There’s a lot of advertising going around saying ‘Our product is better than their product and this is why,’” Grin said. “But in reality, if you do a really good job of installing any one of the systems, they’re going to perform quite well.”


Cellulose insulation being installed in the attic of a Colorado home, bringing the R-value up to R-38. (Photo: courtesy Department of Energy, Weatherization Assistance Program)



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