Can you install a metal panel roof on plastic furring strips?
I am getting ready to install a metal roof (36″ wide panels) onto my SIP roof. I’ve read that a ‘cold roof system’ is the way to go with SIPS – to allow any moisture that comes through the sips to evacuate. Is the extra layer of sheathing over the furring necessary, wouldn’t you get more ventilation if the roof was installed just on furring strips? And could these stand alone furring strips be the plastic Cor-a-vent Sturdi-strip product to allow for better drainage and ventilation? Does this product make for a weaker connection of the metal panel to the sheathing? Is it better to go with wood furring strips and then how do you allow for drainage of any water that does get beneath the metal roof? I also worry about the wind uplift potential that may increase with putting the metals panels on furring? This is for a tiny house on wheels and will need to be able to handle strong winds during the one or two times I need to move it to another location.
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Replies
Rene,
Through-fastened metal roofing is installed on furring strips all the time. These "furring strips" are installed parallel to the ridge, and are usually called "purlins." You can use 1x4s or 2x4s. You don't need any plywood or OSB above the purlins; metal roofing can be attached directly to the purlins.
If I were you, I wouldn't experiment with plastic furring strips. But I suspect that plastic furring strips would work, as long as your screws were long enough for secure attachment.