Exterior Insulation R-Value in Mixed-Humid Climate
user-6445625
| Posted in General Questions on
Hi,
We are designing a wall assembly for a new home in Suffolk County, NY, which is a mixed humid climate (4A). One option we are considering is:
2×6 wall with R23 Rockwool batt cavity insulation
zip sheathing
rain screen or cedar-breather
cedar shingles
Two questions:
1) to avoid a wet wall, what R value should our continuous exterior insulation be for this zone (4A)?
2) Would something like Intello Plus on the interior be wise here?
thanks!
B
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Replies
All you need per code is R3.75 in zone 4. check out:
https://www.greenbuildingadvisor.com/article/calculating-the-minimum-thickness-of-rigid-foam-sheathing
You get R4 with 1" of EPS which has more permiability than other board insulations for some exterior drying.
Thanks, Paul! Very helpful.
You can get used EPS pretty cheaply but many are using the more expensive mineral wool which does add good fire protection.
Thanks. And the "A" aspect of Zone 4A doesn't impact the way we think about exterior insulation at all?