Air and WRB
deerefan
| Posted in Energy Efficiency and Durability on
I recently read an article on fine home building on a 2018 house they helped build. The house used taped plywood seams as the air barrier and Delta Vent SA as the WRB. Can someone please explain why not use the Delta Vent SA as both? I mean if you have a small penetration in the WRB, it is glued on, so unless it happens to be over a plywood joint (what are the chances of that), it shouldn’t matter as far as air sealing is concerned.
They used Rockwool Comfort Board as exterior insulation, does that have anything to do with it? Thanks for the insight.
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Replies
Hi Deerefan.
Was it the California house? Can you post a link to the article?
Yes, it was the California house.
I checked with Mela Breen, the architect and owner (who is also married to the builder) and she said that on the walls, they did not tape the seams of the sheathing, just used the peel-and-stick WRB, but that on at least one of the low-slope roof planes they did do both. Mela said it was a redundancy that they felt was worth the bit of extra material, which they had on hand.
Thank you for checking. I plan on using a similar approach on my home. We have flat and nearly flat (1:12) roofs. The delta rep, however, did not recommend using a permeable product on such low slopes. He stated that the water will go through if it sits long enough. This leaves me somewhat confused as to what should be done?