Typical scope
- Hot-air welded TPO and PVC seams, patches and full sheet installation
- EPDM splice work with primer and seam tape, plus white EPDM options
- Mechanically attached, fully adhered and ballasted systems
- Membrane thickness from 45 to 80 mil specified to the exposure, not the budget
- Detail work at curbs, drains, scuppers, parapets and penetrations
TPO
Thermoplastic polyolefin is the most widely installed low-slope membrane in North America. It is white by default, so it is inherently reflective and lines up well with California cool-roof requirements, and its seams are hot-air welded, which makes a properly made lap as strong as the sheet. Its weaknesses are formulation-dependent: quality varies between manufacturers, and a heavily weathered sheet needs its oxidised surface abraded before it will accept a weld.
PVC
Also hot-air welded, and the material of choice wherever grease, animal fats or chemicals reach the roof, restaurants, food processing, some industrial exhausts. PVC stays more supple than TPO over time. It costs more, and it must never be placed in direct contact with asphalt-based materials without a separation layer.
EPDM
A cured synthetic rubber, so it cannot be re-melted or welded. Seams are made with primer and tape or with splice adhesive, and surface preparation is everything. EPDM handles UV and wide temperature swings very well and has one of the longest track records of any single-ply. The standard black sheet absorbs heat, which is a real consideration in California; white EPDM exists but costs more.
Attachment and thickness
Mechanically attached systems are fastened through the insulation into the deck, fast and economical, but the fastener rows are stress points and the sheet flutters in high wind. Fully adhered systems are glued across the whole surface, cost more, and perform better in wind uplift. Thickness matters as much as chemistry: a 45-mil sheet and an 80-mil sheet of the same material are not the same roof and will not last the same length of time. Always get the mil thickness in writing on the quote.