Jay J, I think there is a difference between us and yall, but it's only a cooling climate and a heating climate. As I understand the use of radient barriers, is that they are placed under the roof in the attic with space between the decking and barrier. Like on the bottom of the rafters. One manufacturer recommended at least one inch. Most houses have a pitched roof that would allow the heat trapped between the decking and the radient barrier to move upward to exit through a turbine, ridge vent or whatever. This means you would not have the radient barrier at the top of the roof because you have to "funnel" the air upward. The hot air moves with the assistance of soffit vents (generally). The key is to keep the attic ventilated especially in Houston where it's not only hot but humid too. A radient barrier would not be of much use without venting the air. So you're right, heat would build up if it just sits there, and i like the way yall talk.