Metal Roof on SIPs: How to prevent battens from rotting?
I am building my own passive solar home using Faswall blocks with a 12″ thick SIP as the roof. I am going to use metal roofing and have been researching the best was to insure a rot-free roof. I am in the mountains of Colorado where we have high winds but not all that much moisture.
The roof is a 2:12 and a 1:12 shed roof fully covered in Grace Ice & Water Shield HT.
I’ve landed on doing a double batten set up whereby the base layer of furring strips run vertically to the roof pitch to allow for airflow and then a second layer of furring strips to run perpendicular to catch the roofing fasteners – like a #. See attached image
I am concerned about moisture getting under the furring strips with roof contact and rotting those out. Furring strips are also prone to cracking with any kind of fastener so I would probably predrill them all.
I looked at using metal furring channels but those are $1/foot meaning the whole roof would cost $2000 for just the metal channels. Seems a little steep.
Am I over thinking this? Is there valid concern? Are there standard practices for such a setup? Could I simply paint a waterproofing on the furring strip with roof contact (maybe $200 in materials)? Help please!
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