TPO Roofing: What Is It and Is It Right for Your Building?

TPO (Thermoplastic Polyolefin) roofing membranes have become the dominant commercial flat roofing specification in the UK over the past decade. If you're planning a large flat roof, you'll likely encounter TPO in your quotes.

What is TPO?

TPO is a single-ply thermoplastic membrane made from polypropylene and ethylene-propylene rubber. It's manufactured in rolls, typically 1.2–2.0m wide, in thicknesses of 1.2–2.0mm. It's normally white or light grey, giving it good reflective properties.

Heat-Welded Seams

TPO's key feature is heat-welded seams. A hot-air welding gun fuses the overlapping membrane edges together, creating a join that's stronger than the membrane itself. This eliminates the seam adhesive failures seen with EPDM on large installations.

Typical Applications

TPO is most appropriate for: commercial and industrial flat roofs over approximately 100m², flat roofs where a light-coloured, reflective surface is desired, roofs with simple geometry well-suited to lap-welded panels. For complex domestic roofs with many penetrations and corners, GRP or liquid applied systems often offer better value.

Cost

TPO typically costs £60–£90/m² installed on a commercial roof, including insulation. It's competitive with EPDM at larger scales. The heat-welding equipment and training requirement means it's less suitable for small domestic jobs where mobilisation costs are proportionally higher.