Continuous Exterior Insulation for wood stud wall for siding
wmorey
| Posted in GBA Pro Help on
Looking for an r30 wall system / detail for zone 4+ with 2″ continuous exterior insulation using a sheathing not FIPS or Zip system.
From outside to in: siding, 1x airgap w/ rainscreen between ridgid insulation and siding… House wrap between plywood sheathing and rigid foam. Interior 2×6 wall cavity insulation would like to avoid closed cell foam, or dense pack insulation. Would open cell insulation work or would mineral wool be a better bang for the buck?
Did not see a wall detail in the library? Does this exist? Does this work?
Thanks
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Replies
wmorey,
The assembly you are thinking of using works well. The amount of exterior foam is sufficient to avoid condensation. https://www.greenbuildingadvisor.com/article/calculating-the-minimum-thickness-of-rigid-foam-sheathing and you can use ether fiberglass / mineral wool batts, or cellulose.
One suggestion to consider is that with 2" of exterior insulation, you may want to move your WRB (house-wrap) to the outside of your foam. That allows you to run your flashing on top of the foam, rather than right back to the sheathing as you would have to do if the WRB is back there, and makes it easier to integrate with your sill-pans.
Some good information and assemblies can be found here; https://www.bchousing.org/research-centre/library/residential-design-construction-guides/illustrated-guide-r22-effective