What is TPO roofingin construction?

TPO roofing, explained.

TPO (thermoplastic polyolefin) is a single-ply roofing membrane, typically 45, 60, or 80 mil, supplied in rolls (commonly 10 ft and 12 ft wide) and seamed with hot-air welds rather than tape or adhesive at the laps. It is the most common single-ply commercial roofing membrane in the US because of its cost, reflectivity, and weldability. On the estimate, the TPO line is driven by net roof area increased for laps and waste, plus the attachment takeoff: mechanically fastened systems need fasteners and plates on a row spacing set by wind uplift; fully adhered systems need bonding adhesive priced by coverage rate. Cover board, insulation, perimeter and penetration flashing, termination bars, and pipe boots are taken separately. A senior estimator reads the wind uplift and attachment requirements off the roofing details before settling the fastener density, since that quantity moves the labor and material more than the membrane itself.