Should Rafters be Encapsulated by Spray-Foam?
Call this Q&A post at GreenBuildingAdvisor the question that won’t go away, or the case of a confused architect.
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The issue is what constitutes the code-approved application of spray-foam insulation in attics. Although we’ve grown used to seeing installations that competely encapsulate rafters, there are still questions whether this practice is in compliance with building codes. The issue isn’t thermal performance, but whether these roof assemblies could pass muster on a fire-safety basis.
Equipment used for standard flame-spread tests has some limitations, meaning that manufacturers must look for alternate test approaches. In some cases, foam must be covered by fire-resistant barriers.
In the end, local building inspectors have the last word, and they may want to see some documentation before approving plans.
This long-simmering debate is the subject of this Q&A Spotlight.
Foaming the roof. How much foam can be applied to the bottom of a roof deck and still meet building code requirements? The question continues to generate confusion.