Insulation Over Roof Sheathing

First since i only have a single layer of asphalt shingles on my roof am i able to just apply the foam right over the shingles or do i need to strip the roof first.

Insulation over roof sheathing.

Water is insulation s enemy. Open or closed cell spray foam is applied to the underside of the roof sheathing and additional fiberglass or cellulose insulation is blown in as a cost saving method for meeting high insulation requirements and filling in the cavity space between the rafters to the ceiling deck. Featuring integrated moisture air and thermal protection zip system r sheathing completely reimagines traditional wall assemblies by streamlining exterior water air and thermal management. Also note that a new fully adhered membrane is installed on the original roof deck replacing the one installed 17 years ago is folded down to catch the top edge of the wall water control layer.

Johns manville r panel rigid roof insulation board offers r values of up to r 23 6 providing high thermal efficiency. Foamular insulating sheathing is xps insulation is used as sheathing over all exterior walls in wood or metal framing construction to create an effective insulating envelope over the entire structure. Insulated roof assemblies can be vented or unvented. There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing.

The screws must be long enough to penetrate an adequate depth into the roof framing. Plywood or osb roof sheathing can be installed over exterior insulation layers using long exterior grade screws. An unvented roof cladding substrate e g. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.

I m considering adding a layer of insulation to the exterior of my roof then another layer of sheathing and finally asphalt shingles. There are lots of different ways to insulate this type of roof but one of the best methods calls for the installation of rigid foam insulation above the roof sheathing. 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. Foamular family of products brochure pdf 7 13 mb.

Box out light fixtures.