PPGL is specified in two layers: the metallic substrate (galvalume, with its AZ coating mass and base-metal grade) and the paint system on top.
Paint system
- RMP (regular modified polyester) — standard building applications
- SMP (silicone modified polyester) — better colour and gloss retention
- PVDF — premium, for severe exposure and long-term colour stability
State top-coat and back-coat requirements (dry film thickness in microns) if the specification defines them, and the colour.
TCT and BMT
Roofing thickness is quoted either as TCT (total coated thickness, including metallic and paint coatings) or BMT (base metal thickness, the bare steel). A 0.50 mm TCT sheet has less steel than a 0.50 mm BMT sheet. Confirm which one your drawing or BOQ refers to before comparing quotations.