Report: With proper installation, all insulation materials perform equally well

Building insulation of all types performs equally well if they are properly installed and sealed, according to a new study from Building Science Corp. 

The Thermal Metric Summary Report, released 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. The finding is contrary to popular belief among builders and installers that insulation quality varies depending on the material. 

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

Among the relevant findings:

• Air sealing is required for all insulation types to provide the optimal performance. 
• During decommissioning of the open cell spray foam wall, the researchers confirmed there were areas where the foam did not adhere to the OSB sheathing, resulting in large voids that can affect performance. 
• Energy losses due to thermal bridging occur with all insulation types, and this effect impacts all insulation types.