Exterior XPS screws vs glue
So on a prior question I asked about condensation risk on the tips of screws that penetrate the sheathing when fitting 4″ of exterior XPS. This applies to both roof (polyiso) and walls (XPS).
I didn’t really get an answer to that.
So I am considering hardly using any screws and fully adhering the foam to the sheathing / deck.
This is maybe not so green in that I don’t have a no-VOC option for the roof, and the costs go up, and it is more risky since I am not aware of it being done elsewhere in the case of walls (it is normal for roofs).
So if anyone has a better solution to condensation on the screw tips when in a retrofit application where the interior finish cannot be touched, I would really really like to hear it. Especially as work starts on Monday 21st.
My climate: 5600 heating degree days, average low Jan temp 20F.
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Replies
Mark,
No advice from me....
Have you tried the JLC Forum or the Breaktime Forum?
Darn, John I don't know whether to thank you, because now I've got two more forums to read, or curse you because I'm going to be up all night reading them! Anyway I will look on the bright side and thank you.
Even more thanks if anyone can come up with a good solution.
Could the paper facing (vapor retarder) on the fiberglass batts be my savior here by reducing vapor flow into the assembly enough to stop condensation? After all risk of condensation occurring shouldn't be much more than on the current sheathing.
However, if there is condensation on the screw tips the kraft paper will make it harder to dry out.