In this latest podcast of If Walls Could Talk, PUR Consulting’s Thomas Harris chats about the performance path vs. prescriptive path as it relates to spray foam.
In previous podcasts, we’ve talked about some of the product myths and we’ve touched on vapor control layers and the role different spray foam materials play in providing an inherent vapor control layer. Open cell foams are vapor permeable, while closed cell foams are vapor impermeable—a Class II vapor retarder.
Contractors often use the various performance path options to downgrade the thermal insulation package in exchange for various upgrades within the building envelope or the entire energy performance of the structure.
Section R406 of the 2015 IECC is entitled “Energy Rating Index Compliance Alternative” and it allows for non-prescriptive code compliant construction – like less R-value in the thermal envelope provided the entire structure is better than the reference standard.
The reference standard is the 2015 IECC uses the 2009 IECC performance standard as a comparative reference.
