What is involved
TPO, EPDM & PVC Membrane Systems: what to expect
Single-ply membrane dominates commercial low-slope construction, but the three common systems are
not interchangeable and cannot be mixed. TPO and PVC are thermoplastics: repaired
and seamed with a hot-air welder, probe-tested along the weld, typically light-coloured and reflective.
EPDM is a synthetic rubber, usually black, seamed with adhesives and seam tape. A contractor who
proposes caulking a thermoplastic seam does not own the right equipment.
Choosing between them
- TPO, reflective, weldable, widely specified, good general-purpose choice in a hot climate.
Performance varies significantly with membrane thickness and installation quality.
- PVC, the usual answer where grease, oils or chemical exhaust hit the roof, such as
restaurants and some manufacturing. Also weldable, generally more expensive.
- EPDM, very long field track record and excellent low-temperature flexibility, but a black
surface absorbs a great deal of heat in Texas unless a reflective coating or ballast is used.
Attachment matters as much as the membrane
Membrane is only half the system. How it is attached, mechanically fastened, fully adhered, or induction-welded -
determines its wind uplift performance, and wind failures on Texas commercial roofs almost always start at the
perimeter. Edge metal, coping and termination detailing should be specified to a recognised wind design, not
improvised.
Protect what you have
Walkway pads along service routes, a roof access log so you know which trade was up there and when, and two
inspections a year will extend the life of a single-ply roof more than any product upgrade.
