thomas smith
2/21/2015
I have a beachfront home in Baja, mexico. The existing roof is imitation Spanish tile panels screwed to 1 x 4 purlins on 2 x 6 rafters. No insulation, no ceiling. I would like to replace the existing roof with locally available galvanized panels. My thought was to install 1" polyisocyanurate panels to the purlins and attach the metal to the purlins by screwing through the insulation board.Can I place the metal directly on the insulation board? If I use foil faced board should I install felt between the roofing and the roofing to keep dissimilar metals seperate? Should I add a second set of purlins between insulation and insulation?
Eric Novotny
An informed customer is the Best Customer!
2/21/2015
Are the rafters exposed from inside the home? Is there plywood decking between the purlins and the rafters?
Gary Shamblen
3/4/2015
MY LOCATION IS IN WV BUT NOT IN MOUNTAINS. WANT A NEW METAL ROOF INSTALLED. HAVE EXISTING SHINGLES, MY QUESTION- SHOULD THESE SHINGLES BE REMOVED DOWN TO THE SHEETING AND A MOISTURE BARRIER INSTALLED AND THE METAL ROOFING ON TOP? IS THIS THE BEST WAY OR IS THERE ANOTHER?
Todd Miller
Isaiah Industries, Inc.
3/4/2015
Gary, that is certainly an option. There are also many metal roofs available which can be installed over existing shingles (with a new layer of underlayment).
thomas smith
5/18/2015
No insulation.rafters,purlins and underside of roof tiles are exposed to the interior.house is unheated and not air conditioned. TC Smith
Eric Novotny
An informed customer is the Best Customer!
5/20/2015
Thomas, You can, in theory, attach your metal right over 1" foam. The issue there can be installation and the fasteners can easily be over torqued and create distortions in the metal. It is easiest to install over solid decking at the end of the day. More insulation (2") would be helpful should you want to condition that space in the future.

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