Introduction
TPO (thermoplastic polyolefin) is a pre-formed, single-ply membrane used extensively on industrial and commercial roofs including PEB structures and metal decks. It is UV-stable, heat-weldable, and resistant to pollutants, making it suitable for exposed applications and rapid installation.
Advantages
- UV and weather resistant, can remain exposed
- Hot-air welded seams provide monolithic, testable joints
- High elongation and tear strength
- Rapid installation with mechanical fastening
- Twin-colour signal layer simplifies damage detection
- Compatible with green roofs when detailed with root barriers
Limitations
- Requires skilled crews and hot-air welding equipment
- Not optimal for small, congested roofs
- Puncture protection required during and after installation
- Fastening design and substrate preparation are critical
Types
- Mechanically fastened TPO membranes
- Fully adhered TPO membranes
- Fleece-backed variants for adhered systems
- Thicknesses typically 1.2–2.0 mm, reinforced or non-reinforced
Application / Method Statement (Mechanical Fastened Summary)
- Prepare substrate: Remove sharp edges and debris. Install vapour barrier if required.
- Fix insulation boards: Rockwool, PIR, or EPS as per thermal design.
- Lay membrane: Unroll with 80–100 mm overlaps.
- Fasten: Screws with stress plates as per wind uplift design at seams.
- Weld: Hot-air weld overlaps using automatic welder. Verify welds with probing and sample tests.
- Detail terminations: Parapets, penetrations, and drains with preformed accessories or strips.
Decision Guide
- Large metal deck roofs with speed priority → mechanically fastened TPO
- Roofs requiring high reflectivity and UV resistance → exposed reinforced TPO
- Complex detailing on small roofs → consider liquid-applied membranes
- High wind zones → engineered fastening patterns and reinforced grades
Acceptance criteria
Substrate and insulation fastening as per design. Wind uplift fastening pattern documented.
Seam weld quality verified by probing and sample peel tests.
Membrane thickness confirmed per product grade.
Terminations at parapets, penetrations, and drains detailed and inspected.
Protection against puncture provided where required.
QA records captured. Weld logs, fastener counts, photos.