Permeable Waterproofing for foundation & impermeable for roof?
Emel
| Posted in General Questions on
I was wondering if anyone had a good recommendation for a liquid applied water proof memberaine for a foundation exterior? It’s a new build and insulation followed by Delta-MS would go over it. I was thinking there was a product like LWM200 or something but I can’t find the name now.
Also, my understanding for a vented roof, where the attic is insulated well, but the roof itself is not insulated (no insulation over the plywood sheathing), it is best to go with a non-permeable membrane underneath a metal roof to prevent condensation and moisture issues. Is that right? Does anyone have a good recommendation for this?
Thank you!
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Replies
Emel,
FWIW, local code where I am requires high temp ice and water shield under the whole area of metal roofs. We are however in a snow and ice environment, which you may not be. If not in a cold icey region then I would still opt for an impermeable high temp rated roofing membrane to prevent the sheathing from picking up condensation under the metal roofing. The sheathing would be able to dry to attic, but why chance a problem. The rate of transfer through a permeable membrane and sheathing might not be to your advantage long term.
Regarding the foundation, it would appear that you are doing exterior insulation. Hopefully, the Delta-MS would provide relief for bulk water at the insulation face so any coating on the foundation wall itself would be a belt and suspenders situation. Having been through a similar build I would ask how you plan on attaching the foam insulation and the Delta-MS as well as the details for above grade areas and transition to main cladding choices.
Getting all the details right before you build will go a long way toward success. Any hints on climate?
Emel,
+1 on all of onslow's advice.