TOPIC: Energy Efficiency
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I have an awkward little house in Phoenix, AZ. Imagine an A frame then cut it in half and add a little room above it. The 80's were a strange time. The majority of the roof is one big south facing plane. Brilliant, I know, lol. To make matters worse, the whole house has vaulted ceilings, very little insulation and no attic on the south side. It has a single layer of shingles from 1983. My dad and I would like to get supplies for a metal roof and DIY it. He is a contractor and Journeyman. What would be the best way to insulated it? We are thinking white tin on purlins and battens with spray in foam. Should we remove the shingles or put it all on top. I saw hard foam metal panels online, but it looks like they are only for commercial buildings. I work for a solar company now and we are planning on putting solar panels on top. Having a large south face works to my advantage for solar, but it is at 45 degrees. Weight isn't really a concern with solar, the panels are so light. But the lag bolts for the racking that holds the panels is a concern. We were thinking of an air pocket, but with bees and rats in Phoenix, it would be hard, even with netting to keep them out. The highest peak is where the air handler is, which is terrible, lol. It has no insulation or drywall in there. I am planning on adding radiant foil to the inside where the air handler is.
Pitch of course is a big factor here as you know all too well. Some good things though include that there does not appear to be any hip or valley.
I think that adding a vented airgap along with insulation and a reflective metal roof would be good. On pitches like this, insulation needs to be blocked to keep it from sliding.
If you built a roof over this roof with, say, 2x6 sleepers along the existing rafters followed by nominal 1/2" decking, you could fill the cavity partially with insulation (perhaps poly iso) and then leave an air gap and vent it. Then your decking, underlayment, and reflective metal roofing.
Yes, the airgap would have to be closed off with mesh or screening or other filter. A thermal break though, especially if vented, is just very effective for such situations.
That said, there are many ways to skin this cat. Always happy to talk through options if you wish to call me. 1-800-543-8938 ext 201
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