Foil Bubble Insulation Under Metal Roof

Green building advisor recently wrote an article about foil faced bubble wrap and did a balanced job of it.

Foil bubble insulation under metal roof.

The r value of foil faced bubble wrap is so low that it has few if any advantages over rigid foam. Foil insulation underlayment is recommended under a metal roof and in most cases the shiny side should be facing up but there s a catch. The main one in the latter category is foil faced bubble wrap sold as insulation. This insulation performs exactly the same as ecofoil double bubble foil insulation the white is just a cosmetic difference.

Unroll the foil bubble wrap insulation over the metal joists or purloins that create the frame for the roof. The question to ask yourself is do i want a foil interior or a white interior ecofoil double bubble white insulation is primarily used in pole barns metal buildings basement walls crawl spaces and storage units. Foil insulation is a radiant barrier and it works by. Most brands of foil faced bubble wrap are only 3 8 inch thick or less and have an r value of only 1 0 or 1 1.

Looking at the table of insulation values bubble wrap and foil will have limited benefit on reducing heat loss. There is no contained air gap inside the foil and the air gap outside the foil is fairly leaky i don t think that there will be much benefit from the insulation value of the bubble wrap. A secondary method of installation instead of installing under the attic rafters is to lay the foil insulation over the attic floor. When i wrote about my trip to the southeast building conference in july i mentioned how some products on display there really annoyed me because they re either bad to the bone or overhyped.

This is why we recommend ecofoil bubble insulation for most metal building applications. Achieved by attaching to the underside of 2 x 4 roof purlins creating a 2 enclosed air space between bubble insulation and metal exterior roof.