AC hacker and GTO,
Yes, I agree that most of the roof heat will transfer via radiation. I didn't realize the % was so high.
A little back ground. If you search my old posts, you will see that we were building a house a year ago. Right before we moved in, that house was lost to fire. We were not insured since I was building the house. This is the rebuild so money is VERY tight.
I would love to put a radiant barrier on top of the foam, leave an air gap and then put on the metal but the radiant barrier is out of budget. The foam is used so it does have some nail holes in it. So for my build, it will be OSB decking on top of the rafters. Then Grace Triflex as the roof underlayment. Set the foam on top of that. After foam will be verticle 1x4 boards with horizontal 1x4s on top of those. Then the metal roof. I'm hoping that will let any water that gets past the roof out and also let air enter low and take the heat out at the top. Yes, my silver roof will pick up some heat but with the air gap and the color and the foam, I'm 100% better than most of the roofs in TX. Most are vented attics with black asphalt shingles, along with the AC system up there!
With all that said, I do have some old rolls of radiant barrier from the first build that was in the fire. They are pretty bad off but I think if I unroll some of it, I might get to clean material. If I do, then I will use some on the south side of the roof! My house faces solar south so it will do the most good there!
thanks
Austin
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