I have a client here in Hawaii with an uninsulated attic and an asphalt tile roof. We have installed several solar powered fans to cool off this space and draw from the master bedroom through two vents in the ceiling. The bedroom is still too hot to be in during the day. One roofer has suggested taking foil backed insulation and reversing it so the foil is againt the plywood roof decking. Will this help to cool the attic or just hold more heat in? Any other ideas on how to cool off the attic?
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I've never heard a convincing argument that foil does any significant amount of good as an "insulator" in a closed space. But insulating the roof (with ventillation of the attic space) is probably a good idea from a heat-gain standpoint (though possibly not from a roof durability standpoint). Of course, insulating the attic floor would probably be just as effective.
Hoohuli,
I think the problem is the lack of insulation. You are getting radiant heat gain that won't go away no matter how much air you move. Install a radiant heat barrier on the bottom of the rafters with the foil facing down and insulate with fiberglass or blow some cells. Soffit and ridge vents should help also.
http://www.ornl.gov/sci/roofs+walls/radiant/
KK
Mahalo for your reply, any names of brands of radiant heat barriers come to mind? Insulation is not a big seller over here so I'll have to see what's out there. We are moving alot of air with 14 attic and roof fans going all day. It was 88 dg. in the room today with everything pulling air.
Radiant barrier looks like aluminum foil bonded to a tough paper. Don't remember a brand.
You are fighting a losing battle trying to control radiant heat by moving air.
KK