Most homes have one roof...pretty normal, right?
A few years back I was talking with a roofer about how heat is the big killer for most roofs. I half-jokingly said that we should just build a shade over the roof to protect it. Something like a second roof that takes all the sun damage and weather and preserves the 'real' roof.
Well, basically that is what we have done here. We have your typical 1/2" plywood roof that we have air sealed. Then we added another structural layer to this to hold more insulation. On top of this we added a weather protection layer made out of wood fibers and wax called Agepan. Above all this we added a vented cavity for drying and another 1/2" plywood layer!
So where I was joking about 2 roofs, we actual have 3 of them on this project! 1-structural, 2-Vented Thermal Barrier, 3-Weather-Proof Top Layer with a metal roof on this...Hmm we may officially have 4 I guess!