Installing Self adhered roof underlayment on wet sheathing
AdamPNW
| Posted in General Questions on
Hi all, currently installing plywood roof sheathing, but the wet season is upon us here in the PNW. Was planning for a self adhered roof underlayment, with metal roof. Will the underlayment stick sufficiently to wet sheathing?
I checked installation instructions with a couple manufacturers, and they simply say apply to “clean and dry surface”.
Thanks, Adam
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Replies
think you already know the answer is "no, it's a bad idea" to apply peel and stick to a wet surface. adhesion issues aside, you are forcing wet material to dry to the inside and this would be more difficult where the sheathing is in full contact with the framing system.
check with the metal panel manufacturer for minimum warranty requirements and whether you can use a huber product and tape the seams -- [unlikely]
the dumb, expensive way to install in wet weather would be to pre-apply onto sheets of plywood; install; then strip in the seams or apply a whole second layer or underlayment.
Adam,
If the sheathing is also an air-barrier it gets complicated as tapes on the sheets won't adhere well in the wet either. If not I'd switch to an impermeable underlayment rated for metal roofing, and use cap nails to secure it.
Thanks Malcolm, my air barrier will be the Intello membrane at the ceiling plane. So I think switch to cap nails.
What brand underlayment do you like for that application?
Adam,
I've never noticed any difference between the brands, and use whatever my lumberyard is currently stocking.