| Membrane | Seam | Best For |
|---|---|---|
| TPO | Hot-air weld (450–550°C) | Primary flat roof — reflective, low cost |
| EPDM | Splice tape / adhesive | Renovations, long UV life |
| PVC | Hot-air weld | Chemical exposure (kitchens, generators) |
PVC and TPO are incompatible — cannot be welded together. Use transition strip.
| Item | Spec |
|---|---|
| Panel gauge | 24 ga steel (Galvalume) or 0.032" aluminum |
| Panel width | 305–457 mm (12"–18") |
| Seam height | 38–50 mm |
| Seam type (worship) | Double-lock mechanical seam |
| Clip spacing | 600 mm o.c. typical; tighter in high-wind |
| Clips | Fixed at ridge, sliding toward eave |
| Underlayment | 100% ice & water shield (HCMI standard) |
Snap-lock only on non-visible utility buildings. 308A required for all fabrication.
| Type | R/inch | Use |
|---|---|---|
| Polyiso | R-5.7 (derated) | Primary flat-roof insulation |
| EPS | R-3.8–4.4 | Tapered systems, ballasted |
| XPS | R-5.0 | Below-membrane (IRMA) |