Minimum Thickness Rigid Foam Sheathing in Zone 4A
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Hello
This article
https://www.greenbuildingadvisor.com/article/calculating-the-minimum-thickness-of-rigid-foam-sheathing
specifies a minimum of R3.75 exterior rigid insulation for a 2×6 wall in climate zone 4-Marine to prevent interior condensation. I am in Zone 4A (mixed humid) and NOT “marine”. Does anyone know if this number still applies? And if not, where do I find a more relevant R value?
Thanks!
Brad
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Replies
Ok, I found a resource for this. https://www.continuousinsulation.org/content/2021-ibc-irc-adopt-improved-vapor-retarder-requirements
"2021 IBC includes all of Zone 4" - so not just Marine.