Zip sheathing under metal roof
AdamPNW
| Posted in General Questions on
Hi all, a zip rep told me that zip sheathing is ok to use directly under standing seam metal roof (unventilated ) if the slope is 4/12 or greater. Otherwise a separate underlayment is suggested. This didn’t make sense to me except that perhaps flat roofs may need extra protection from water intrusion, but heat?
Does anyone have any experience with zip under under metal panels on a hot roof (zone 4 marine).
Thanks!
Adam
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Adam,
Have you seen this?
https://www.huberwood.com/uploads/documents/technical/When-Is-High-Temperature-ZIP-System-PSU-Necessary.pdf
Thanks, that’s very useful.
I’m thinking I don’t need any additional underlayment on top of the zip since my roof is a 6/12 simple gable, and we don’t get any appreciable snow build up here on the Olympic Peninsula.
I would tape the seams (and the eave/rake edges with 9” wide tape).
But if I did use an extra underlayment I would spec high temp.
Does that all seem reasonable?
The rep must have been talking about water intrusion with regard to pitch. She had led me to believe that the zip coating itself could suffer at higher temperatures at lower pitches.
Adam