Quick definition
Thermoplastic polyolefin: a single-ply membrane, usually white, with heat-welded seams, widely used on commercial low-slope roofs.
TPO is the membrane on a large share of new commercial flat roofs. It's usually white, it reflects heat, and its seams are welded with hot air rather than glued.
What is TPO?
TPO (thermoplastic polyolefin) is a single-ply roofing membrane made from a blend of polypropylene and ethylene-propylene rubber, reinforced with a polyester scrim. It comes in rolls, usually white, though gray and tan are also made. Common thicknesses are 45, 60 and 80 mil.
How is a TPO roof installed?
The membrane is laid over insulation and a cover board, then secured in one of these ways:
| Attachment | How it works |
|---|---|
| Mechanically attached | Fasteners and plates along the sheet edges, covered by the next sheet's seam |
| Fully adhered | Bonded to the substrate with adhesive across the whole sheet |
| Induction welded | Plates under the membrane are heated by an induction tool and bond to it, with no fasteners through the sheet |
Seams are joined with a hot-air welder that melts the two sheets together. A good weld is as strong as the membrane itself.
What are the pros and cons of TPO?
Strengths
- Reflective white surface keeps the roof and building cooler.
- Heat-welded seams are strong and don't rely on adhesives or tape.
- Cost-competitive with other single-ply membranes.
- Formulations vary by manufacturer, and early TPO products had weathering problems.
- Seam quality depends on the installer's welding skill and settings.
- Like all single-ply membranes, it can be punctured by dropped tools or foot traffic.
Where is TPO used?
TPO is used mainly on commercial, industrial and multifamily buildings with low-slope roofs, and sometimes on flat sections of homes. Its reflectivity makes it a common choice in hot climates.
TPO vs EPDM vs PVC
| Membrane | Color | Seams | Known for |
|---|---|---|---|
| TPO | Usually white | Heat-welded | Reflectivity and value |
| EPDM | Usually black | Taped or glued | Long track record, flexibility |
| PVC | Usually white | Heat-welded | Resistance to grease and chemicals |
What it means for you
What TPO means for homeowners
If you have a flat section on your home, TPO is a common option. Ask the roofer about membrane thickness, how it will be attached, and whether seams will be probed after welding.
Frequently asked questions
Sources
- TPO manufacturer product data and installation instructions. Technical Reference.
Tier 1 authority 路 manufacturer - The NRCA Roofing Manual: Membrane Roof Systems. NRCA.
Tier 2 authority 路 industry - SPRI single-ply roofing technical resources. SPRI.
Tier 2 authority 路 industry