Framing A New Roof Over An Old Roof

A new level 2 6 ridgeboard and rafters then are assembled over the old roof and are attached to the existing structure with nails and lag screws driven into the underlying wall top plates.
Framing a new roof over an old roof. Installing the new roof. The sheathing must be stripped from the old roof for a couple feet along the bottom to get the new ceiling joists in. You can frame a new roof over the old but it will need to be designed for the span and pitch. Use 1 5 or 1 75 inch roofing nails.
Closed cell polyurethane foam insulation is sprayed around the new roof frame sealing edges and providing support for the rafters and the ridgeboard. Or if you want to raise the roof a bit more install fascia around the roof perimeter attached to the new soffit and nail the new roof deck to crown molding above the fascia.