Corrugated metal systems?
I’m planning a small structure in hot, humid Florida (climate zone 2). In contemplating materials for the roofing and siding, corrugated metal appeals to me because it’s affordable, green, and provides two specific advantages that Florida needs: strength against hurricane debris impacts, and the potential for a reflective surface coat to mitigate heat gain.
How would you design a green, efficient, dry roof and wall system using corrugated metal for both roofing and siding? I have two constraints: the building’s small footprint renders a double stud wall system ‘out of the question’, and spray foam insulation is not welcome.
Thanks for your consideration!
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I don't know enough about your climate to be of much use, but I will make a couple of observations about corrugated metal siding. Installed vertically and vented at the bottom it forms a good rain screen, so that unlike many other impervious claddings it allows the wall to dry to the exterior. Be careful about how you install it. The most common siding material, Galvalum, is extremely susceptible to damage when in contact with treated ACQ lumber.
Thank you, Malcolm. I was thinking the corrugations might be used to that advantage on the vertical, and thanks for the warning on contact between Galvalum and treated lumber.
I like the idea of using structural grade Thermo-ply as wall sheathing as it, too, is green, affordable, and eliminates the extra step of installing a separate housewrap. The prospect raises some questions though...would an underlayment be needed between the Thermo-ply and the corrugated metal? Would it be sufficient to screw the corrugated metal 16"OC, as I don't think Thermo-ply is suitable as a fastening base...
Andrew,
You'll need to think through your window flashing details carefully before proceeding with your plan. I assume that you will install some type of structural sheathing under your metal siding.
All walls need a WRB. I have never heard of Thermoply being used as a WRB. I think you'll probably want housewrap or asphalt felt as a WRB.
If you don't want to build a double-stud wall, I suggest that you consider installing a layer of exterior rigid foam to interrupt thermal bridging through the studs.