Rigid Foam Roof Sheathing

It spans the rafters to support the roofing and in the case of panel sheathing such as plywood or osb it acts as a diaphragm with the walls to resist horizontal loads.

Rigid foam roof sheathing.

Installing rigid foam insulation on top of roof sheathing is a great option for commercial buildings and homes with limited space. Foamular 250 2 in. R 5 scored square edge rigid foam board insulation sheathing. Polyiso consists of a uniform closed cell polyisocyanurate foam core and provides one of the highest r values per inch of any rigid insulation.

R 10 scored squared edge insulation sheathing. Foamular 150 1 in. Roof sheathing attaches to the surface of the rafters or trusses to form the structural skin of the roof. Nail it around the edges with roofing nails.

If you have a vented attic it makes no sense to install rigid foam above the roof sheathing. Foamular 150 1 1 2 in. 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. Rigid foam over roof sheathing we are in the process of building a home with all the ceilings in the house paralell to the roof and used 2 x 10 rafters throughout.

1 inch and 2 inch thicknesses are common. Apply continuous air control membrane to existing roof sheathing or implement continuous air control at roof sheathing. Many homes in more urban areas or other places with dense populations are opting for this method because they can better optimize space. You might as well put the rigid foam in the branches of a tree in your back yard.

A vented attic is basically outdoors so installing rigid foam above your roof sheathing is a waste of money and a waste of rigid foam. Exterior rigid foam improves air tightness adds r value reduces the chance of condensation in wall cavities and greatly reduces thermal bridging through studs. The boards are available in several thicknesses and r values. Install rigid insulation board in multiple layers with joints offset vertically and horizontally between adjacent layers.

Not only that foam sheathing will soon be mandated by code in some climate zones. To lessen heat buildup in the summer we installed dupont tyvec attic wrap on the top of the rafters and then nailed 1 furring strips on top of the rafters then installed the. Johns manville polyiso foam sheathing insulation boards provide a continuous layer of insulation to reduce thermal bridging and improve energy efficiency.