insulation under R-panels

Harry Meyers
7/19/2012
I'm building a small 8' x 8' storage shed. Plan to use 26 gage R-panels on roof and sides. Condensation is a big problem with metal building down here. Can I install the rigid insulation board under the panels instead of the bubble wrap? How tight should the screws be installed? I don’t see a problem with the siding, but am concerned about the roof! Thanks
David Stermer
7/23/2012
Harry, Thanks for the question and your interest in metal. Certainly a properly installed rigid board insulation will address condensation for tyher typical building.This would include taping the seams. The fasteners can be tricky. The screws need to be tight enough to engage the washer, but not so tight that the fastener dimples the panel. In standing seam applications I have seen bearing plates used to reduce the compression fo the insulation. Best regards, David Stermer
Eric Novotny
An informed customer is the Best Customer!
7/24/2012
As David mentioned, get the air barrier details (i.e. sealing of the foam) done nice and tight and you should not have any air movement to the back side of the metal and therefore avoid most of the sweating potential. Here is a picture of a foam specific screw and washer assembly.

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