When sourcing aluminium roofing, you must prioritize material grade, typically 3000 series (like 3003 or 3004) for excellent corrosion resistance or 5000 series for marine environments. The thickness (gauge) usually ranges from 0.5mm to 1.2mm; thicker panels offer better structural integrity against wind loads. Additionally, verify the coating type, such as PVDF (Polyvinylidene Fluoride) for superior UV resistance and color retention, or PE (Polyester) for indoor or less demanding outdoor applications.