New Flat Roof Installation - Residential Single-Ply Membrane

Residential flat roofs come in different scopes. Some are full-building flat roofs on mid-century or modernist homes. Some are flat sections within a larger pitched roof - typically over a porch, an addition, or a section where the original architect ran out of headroom for a pitched roof.

This was an eight-photo project on a residential flat section. The previous roof was a hot-mopped built-up bitumen with about 20 years of service life. It had reached end-of-life: alligator cracking across the field, a small ponding area at the drain, and the gravel surface had eroded down to bare felt in spots.

Replacement system: tear-off down to deck. Two inches of polyiso insulation, mechanically fastened with code-spec fastener density, for an assembly R-value of about 12 (the original assembly was uninsulated). DensDeck cover board mechanically fastened over the insulation. Single-ply Polyfresko membrane fully adhered. Heat-welded seams with a hot-air robot welder. Pre-fabricated corners at the parapet inside corners. New metal edge with hooked drip flange around the perimeter. Pipe boots welded to the field membrane at every penetration.

Eight photos document the tear-off, the insulation, the cover board, the membrane install, the seam welding, and the finished roof. The white Polyfresko brings the house into compliance with current Title 24 cool-roof requirements.