metal roof over Zip panels

Jim Wright
Has anyone used Zip panels on their roof and then installed metal roofing ? I'm about to install standing seam metal roofing on the Zip panels on my roof. At first, I was going to install the roofing directly over the Zip panels as per Huber's (Zip manuf.) suggestion, since the panels already have the Zip weatherproof membrane bonded on the surface. Later on, I got to thinking that I would first put down a synthetic underlayment (Grace Tri-flex) just for extra protection. After thinking more about it, however, I now wonder if maybe the underlayment is not only not necessary but that I would be better off not putting hundreds of more holes through the Zip panels with the cap nails for the underlayment. Now I'm back to thinking that I should just put the metal directly over the Zip panels. The Zip panels have been on for about 5 months already and so far have been watertight. Anyone have any thoughts about it ? Thanks, Arky
Todd Miller
Isaiah Industries, Inc.
My recommendation is to still use underlayment. Let's see what others say.
Eric Novotny
An informed customer is the Best Customer!
I would run an underlayment as well. If you are worried about the holes through the panels, snap chalk lines on the rafters and only put them through at the rafter locations. The benefit to a long roll of underlayment is the lack of seams (contrary to Zip panels) and the stepped effect of the underlayment (i.e. like a flashing effect).

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