A lasting finish on a metal roof depends on the condition of the sheet and the coating beneath it. Identify the existing finish, remove loose material and repair damaged areas before choosing a paint approved for that substrate. Check the sheets, flashings and fasteners, and trace the source of any staining. Holes, defective laps and weakened supports need repair before painting. Where corrosion is extensive, compare refurbishment with replacing the affected sheets. Have the contractor responsible for the work assess the coating, plan safe roof access and check that the forecast meets the paint system’s requirements during application and drying.