Putting 1 Foil Faced Ridig Board Under Attic Roof

Installing rigid foam insulation.

Putting 1 foil faced ridig board under attic roof.

If you want to use them without creating a vapor barrier look for permeable iso panels faced with fiberglass. Then a second layer of plywood sheathing and asphalt shingles following the steps explained in this article. Cut ap foil faced foam sheathing to fit snuggly between the rafters. Johns manville r panel rigid roof insulation board offers r values of up to r 23 6 providing high thermal efficiency.

Foil insulation is a radiant barrier and it works by. 4 of polyiso under 4 of eps all above the original roof sheathing. I have at my disposal four inch polyiso board with the foil facing. R panel is manufactured with a closed cell polyisocyanurate foam core bonded to fiberglass reinforced facers and designed for use over metal nailable and non nailable roof decks with a variety of membrane systems.

2 measure and cut the foam boards as. I have 2x10 rafters. However foil faced iso panels are warranted as impermeable. Multiple layers of foam board may be required.

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. Select rigid foam insulation boards that are at least 1 2 inch less in thickness than the rafter space is deep if you plan to finish the attic as living space. Foam insulation boards are the best material with which to work when undertaking a do it yourself project because foam. Installing foam insulation boards in the attic is no that hard and can save you money compared with professional installation.

My plan was to rip one inch strips of wood to put on the back of the roof decking then cut the polyiso board to fit in between the rafters leaving one inch gap for ventilation as well as a 1 4 inch gap on either side to seal after installation. It provides an r value of 6 per inch of thickness and often comes foil faced to help reflect radiant heat. This is an even more dense and more expensive foam board insulation. The r value of the insulation must meet local building code requirements for unvented attics to prevent condensation.

We live in zone 5 suburb of chicago and are hopefully about to put rigid foam above the roof sheathing on just the northeast roof portion of our roof. Install ap foil faced foam boards between rafters directly against the bottom of the roof sheathing.