Does tarped roof sheathing get wet and need to be dried out before applying membrane?
Hi. I am reroofing a low-slope (2.5:1) shed or lean-to roof over an addition, generally following the principles laid out in Martin’s articles on unvented cathedral ceilings. Although I did decide to cut and cobble, as the inspector wanted a vapor barrier anyway, and I’ll use a smart barrier. I put new 1/2 inch exposure 1 plywood sheathing on, tarped it with a polyethylene tarp clamped at the edges and loose at the eave, but with a few boards on it to hold it down. My plan now is to cover the plywood with ice & water barrier, then 1/2 or 3/4 inch of EPS, then another layer of plywood, and use a self-adhering 2-ply asphalt system such as GAF Liberty.
So here’s the thing – I have been working on the inside for a couple months — that cut and cobble is taking forever, and I don’t get to work on this full time. I’m in climate zone 5, running out of season. We have had a lot of rain. No leaks, but will the plywood be wet from moisture trapped under the tarp? If so, I assume it must be dried out, since once the ice and water barrier is on, it won’t be able to dry inwardly or outwardly. Probably a dumb mistake, should have put the membrane on right away. If it’s got to dry out, how long would it take by just being uncovered on dry days? Should I get a moisture meter, and if so, what moisture levels would be safe?
Thanks for your thoughts.
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