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How to Terminate Under-Slab Vapor Retarder at Walls

Manny_Lourenco | Posted in General Questions on

Good day to all. I love this website, it has such valuable experience. I have read tons on vapor barrier under the slab but have not come across anything on how to terminate it on the walls. So, I am in climate zone 4, basement slab is approximately 31”-33” below grade. I have 2” of 3/4 stone, 2” xps r-10, 15mil vapor barrier, 6×6 wire mesh, and my radiant loops zipped tied to the mesh. Almost forgot 2” perimeter insulation at edges that is only 8” deep, unfortunately that was the best I could do, I guess some is better than none. Also have a dimple corner to allow any water that comes through walls to seep to ground below. I believe I will be using 2” of closed cell spray foam on walls, unless something else is a better suggestion, and just don’t know if I should spray over the poly or leave it out of the wall. If my judgment is correct I believe I should tape it to the foundation walls and spray over the poly. Please let me know if my approach is correct or if I should do something different, Much appreciated. Thank you all.

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