ASHRAE bumps up roof and wall R-value for first time in 19 years.

February 02, 2008 |

For the first time in nearly two decades, ASHRAE has increased the minimum required prescriptive R-value (resistance to heat flow) in ASHRAE Standard 90.1 to R-20 for above-deck roof insulation, from the current R-15 level—a 33% increase. Similar increases were approved for walls. For more, visit

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