Exterior Roof Insulation Details

Insulated roof assemblies can be vented or unvented.

Exterior roof insulation details.

Single ply roof insulation. There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing. Single ply roof systems can provide an easy to install seamless roof assembly. The binder includes product specifications detailed drawings and illustrations technical datasheets and a number of informational brochures.

Rigid insulation layers exterior to existing roof sheathing must provide sufficient thermal insulation r value to control condensation risk see climate specific guidance. Rockwool multifix is a mineral fiberglass faced stone wool product that can be installed under many single ply membranes. Thermalwall ph rigid eps insulation board for insulating the exterior walls of homes the advantages are plenty here panels are between 4 5 inches and 8 inches thick the exterior insulation is continuous and they can be attached with 6 inch 10 screws from 4 to 6 inches long. Nailbase must be vented in high snow load areas.

When insulating foam is used to wrap the exterior of a home it provides an undetected pathway connecting soil to structure. Termites can tunnel from the soil up behind the foam panels and attack the structure of a house without being noticed. Extend the foam 4 inches past the walls so that you can add foam to the walls later and tie it in to the roof. Install nailbase for cladding.

The easiest way to insulate your roof is with one or two layers of rigid foam insulation installed above the roofing. Install two layers of insulation to the roof staggering the seams offsetting the joints and taping outer layer. Roof edge detail overhang extended to hide the thickness of the over roofing rigid insulation. New roof sheathing on top can extend out to create a new roof overhang.

Current building code does provide prescriptive means to attach cladding over exterior insulation table r704 3 note v. Install roofing underlayment flashing and cladding as per best practices. Now comes the really really big point. Current pneumatic nailers have maximum fastener lengths of 3 to 3 5 which limits insulation thicknesses to 1 5 max.

Building codes are clear. Detail drawings illustrations lapolla distributes an architectural binder available in print and electronic format. Minimum nail length must accommodate sheathing and penetrate framing a minimum 1 inches. If you are planning to install metal roofing then you would install asphalt felt above the rigid foam followed by 1x4 or 2x4 purlins 24 inches on center then the metal roofing.