Drying of Zip and Foil-faced
brooksbend
| Posted in Green Building Techniques on
Woke up this morning to loads of dew. The plan was to put foil-faced poly ontop of the zip roof sheathing.
Going to go ahead, use towels/moving blankets to dry off the roof. How concerned should I be about trapping moisture in? Cellulose between rafters then intello, so even though OSB isn’t very permeable it’s permable enough for drying towards the inside eventually, yes? How much so I work to dry the sheathing first?
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Replies
The water-resistant coating on the Zip should have prevented moisture from soaking in, and if vapor drive is toward the interior, which it will be when the interior is relatively cool and sun is beating on the roof, the sheathing should be able to dry readily. I wouldn't worry about it, but if waiting a couple of hours would mean the roof would be dry, I'd find something else to do until then. If it's going to be damp all day, then go ahead and place the foam.
A little moisture probably isn't a big deal. I'd clear off any puddle-like amounts though (i.e. "feels a bit damp" is OK, put when you can SEE an area like a flat puddle, that's a problem). I agree with Michael -- if you can wait a few hours for the sun to dry things off for you, then that's the route I'd take here.
The only potential issue with moisture on the OSB would be around the edges, especially cut edges that may not have been resealed, but if you taped your Zip joints the way you're supposed to, then the edges should be reasonably well protected.
OSB is most at risk at unsealed edges, where water can wick into the panel and cause swelling. The face of the panels is usually less of a concern.
Bill