Rigid Foam Exterior Roof Sheathing

The generic term is rigid foam sheathing or rigid foam insulation and it plays a direct role in a building s energy efficiency and performance.

Rigid foam exterior roof sheathing.

You can even place it under the foundation slab. They keep your home at a comfortable temperature without the need to crank your heat. Not only that foam sheathing will soon be mandated by code in some climate zones. Installed on the roof exterior foam makes the living space below more comfortable and reduces the likelihood of ice dams.

Plywood has an r value of 1 25 and fiberglass batts have an r value of 3 14. A lower layer conventionally nailed to the rafters and an upper layer installed as a nailing surface for the roofing material on top of the rigid foam. Install nailbase for cladding. Then a second layer of plywood sheathing and asphalt shingles following the steps explained in this article.

Rigid foam must be thick enough to prevent condensation on the roof sheathing. More effective insulation with r values ranging from 3 6 to 8 0 rigid foam sheathing has much better insulation per inch than other materials i e. Featuring integrated moisture air and thermal protection zip system r sheathing completely reimagines traditional wall assemblies by streamlining exterior water air and thermal management. 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.

Rigid foam insulation also known as insulating boards provide high r values. Johns manville r panel rigid roof insulation board offers r values of up to r 23 6 providing high thermal efficiency. Here s what you need to know about this growing trend. The illustration shows two layers of osb or plywood roof sheathing.

By patrick mccombe issue 273 feb mar 2018 when combining exterior foam insulation with fiberglass cellulose or mineral wool roof insulation the foam layer must be thick enough to keep the sheathing temperature above the dew point. 3 benefits of rigid foam sheathing. Rigid insulation is one of the best tools to reduce your energy costs. Rigid insulation layers exterior to existing roof sheathing must provide sufficient thermal insulation r value to control condensation risk see climate specific guidance.

Exterior rigid foam improves air tightness adds r value reduces the chance of condensation in wall cavities and greatly reduces thermal bridging through studs. 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. Outsulation is the construction practice of placing a layer of insulation on the exterior side of the building. Install it anywhere from the roof to the foundation.