GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

metal roof over foam

Darren Williams| Posted inGeneral Questionson

hello, I am installing a metal roof over foam sheets, its the box store type panel with exposed screws. the roof is as follows… 7/16 zip taped and sealed to rafters, 2 layers of 2 inch polyiso taped, staggered and sealed and here is where my issue lies, I was going to put down a layer of 5/8 zip, taped and sealed, with long screws going into rafters but all the screws seem to stand a little proud of the zip. I was told this would rub on the roof panels causing wear and/or rust issues. I have used strapping in the past and countersunk the screws, what do you do with sheet goods? I tried lining up the ribs in the panel with the screwa but the rafters are 16″ oc and the ribs are 6″ oc. thanks for any help.
Darren Williams

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. Expert Member
    Akos||#1

    If you are using roofing deck screws, you can get plastic washers for them. This would keep the screw head away from the roof.

    If you are not in a windy area, you can also go with flush mount (bugle head) screws instead of the truss headed ones.

  2. Joel Cheely||#2

    I think a synthetic underlayment may be in order. It would act as a "slip sheet" for the whole roof and a barrier at the screws and the tape. It would also cover any overdriven fasteners.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |