http://ecorenovator.org/forum/solar-...bottom-up.html: See this thread. I'm not a big fan of using multiple layers of radiant barrier. A least here on Earth. Air can easily short circuit multiple layers though the process of conduction and convection. Here on Earth I would limit it two a maximum of two layers with a generous airspace between them. Btw, I'm still working on my project, which is coming along. And for anyone who doesn't know it, if you live in a mild climate then you can use a radiant barrier for both cooling and heating. That's providing your house is quite tight and well insulated. Again, see that thread. I too am sorry to hear of the unfortunate happenings with your previous house.