Dive Brief:

• Building insulation of all types perform equally well, as long as they are properly installed and sealed, according to a new study from Building Science Corp.

• The Thermal Metric Summary Report, prepared in June and released this week by the North American Insulation Manufacturers Association, compared the performance of fiberglass batts, cellulose, closed-cell spray foam, foam sheathing and open-cell spray foam. In a related test of walls that were air-sealed and insulated with R-15 fiberglass batts and R-15 dense-pack fiberglass loose fill, the air-sealed R-15 batts performed better than an R-13 open-cell or R-12 closed-cell spray foam wall.

• NAIMA has also reported that fiberglass batts are less expensive to install than blown-in fiberglass, open- or closed-cell spray foam, or cellulose.

Dive Insight:

The research debunks the prevailing belief among builders and installers that insulation quality varies depending on the material.

“R-value is R-value,” the researchers concluded. “When walls are constructed to the same R-value and properly air sealed, all insulation types perform essentially the same.”

Still, those involved in the Thermal Metric Project — including NAIMA, Building Science Corp. and a consortium of manufacturers — said they are not ready to propose a new metric to replace R-value as the best measurement for the thermal performance of insulation.

And the scientists reiterated an age-old warning: No insulation is sufficient without air sealing, no matter what the product is made from.