There is no doubt that the rigid foam insulation boards you’re installing work. To see evidence, all you have to do is take a modern picnic cooler to a tailgate party. Those coolers typically ...

but in some cases—like in attic insulation—an ignition barrier like 1/4" wood or 3/8" gypsum board is necessary. Burbank says it's because of the fire hazard that he doesn't install foam in ...

But better yet is to install 6-inch Fiberglas insulation with the paper vapor barrier up, touching the boards above. Secure the insulation with pointed wires stuffed between joists, and you will ...