Quote:
Originally Posted by buffalobillpatrick
A strange roofing requirement here, ice & water shield (Grace) etc. must be applied at eaves & extending 6' past the interior wall vertical line.
This is to prevent ice dams (which I won't have, no gutters & 9.7 steel roof pitch)
I believe that this is a bad idea, with my closed cell SPF this will create a double water vapor barrier with 5/8" CDX plywood sheathing trapped in the middle.
Perhaps I will file for a variance on this?
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Ice and water shield does not prevent ice dams. It only provides leak protection from them. This is because the product is fully adhered and provides sealing around penetrating objects. Ice dams still happen even with metal roofs and no gutters.
https://buildingscience.com/document...d-135-ice-dams
In your situation I would probably do a ventilated over roof. Figure 8 in this link:
https://buildingscience.com/document...46-dam-ice-dam
It's not the cheapest solution, but the cheapest solution would be a ventilated attic, and I'm assuming you want your attic sealed and conditioned.