Rigid Foam Under Roof Deck

The snugness of the foam itself should be sufficient to hold the strips.

Rigid foam under roof deck. At r 4 it also has the lowest r value per inch. Unvented attics that are insulated on the underside of the roof deck with blown spray foam. Attach to deck board. Eps is the most vapor permeable of the three types.

Rigid foam is produced in various size panels 4 ft x 8 ft 4ft x 4ft etc. Install nailbase for cladding. Install roofing underlayment flashing and cladding as per best practices. Nailbase must be vented in high snow load areas.

High efficiency attic insulation helps provide added thermal protection lessens wasted energy and increases enhanced comfort and quiet. After the roof deck is prepared the rigid foam boards need to be cut to size to fit snugly together on your roof. And vented or unvented attics that are insulated above the roof deck with rigid foam. The panels need to fit together tightly to help prevent warm air from leaving the top of the building.

All three types of rigid foam insulation expanded polystyrene eps extruded polystyrene xps and polyisocyanurate are suitable for use on the exterior of walls and roofs though they do not perform equally.