Coating designation
Aluminium-zinc coating is specified as total mass on both sides — AZ70, AZ100, AZ150 and similar. AZ150 is the usual reference for roofing and cladding substrate.
Substrate
Galvalume is produced on both forming-grade substrates and high-strength structural substrates (for example 550 MPa minimum yield, often written G550) used for roll-formed roofing. State which one is required: a high-strength substrate will not behave like a forming grade in bending.
Surface
Bare galvalume is often supplied with an anti-fingerprint (AFP) resin coating. Specify it if the surface will be handled or left exposed.