Our local Lowes and Home Depot have that composite stuff at some locations and not others. You could google it and then have it delivered to the store near you if that's what you decide to use. I have metal roofing left over from my house roof that I used on my coops--no issue with the heat. I agree about if you put it over the existing wood it would insulate it and heat wouldn't be an issue. That corrugated metal is the cheapest but you can't cut it with scissors.