Rigid Foam Over Roof Sheathing

The exposed edges of the 3 layers of rigid insulation are no longer exposed.

Rigid foam over roof sheathing.

Installing rigid foam insulation on top of roof sheathing is a great option for commercial buildings and homes with limited space. The illustration shows two layers of osb or plywood roof sheathing. Furring strips on sheathing behind rigid foam would installing vertical furring strips next to the sheathing and behind the rigid foam help the wall to breathe and still maintain r values. Install rigid insulation board in multiple layers with joints offset vertically and horizontally between adjacent layers.

Then a second layer of plywood sheathing and asphalt shingles following the steps explained in this article. Apply continuous air control membrane to existing roof sheathing or implement continuous air control at roof sheathing. 4 of polyiso under 4 of eps all above the original roof sheathing. Installed on the roof exterior foam makes the living space below more comfortable and reduces the likelihood of ice dams.

Benefits of rigid foam on top of sheathing. Box beam gable framing new gable overhang is framed in the form of a box beam hanging off of a new layer of roof plywood roof sheathing cantilevered over the top of the 3 layers of rigid insulation. I am in zone 7 and considering adding foam to the exterior since i am residing. Remove existing roofing and non adhered underlayment to expose roof sheathing.

3 benefits of rigid foam sheathing. Plywood has an r value of 1 25 and fiberglass batts have an r value of 3 14. Or is this just over kill. Nail it around the edges with roofing nails.

Many homes in more urban areas or other places with dense populations are opting for this method because they can better optimize space. Start at the bottom of the roof and place the first piece of rigid foam insulation against the metal flashing starting at the center line. 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. 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.

Thanks for any replys.