The first step is a thorough inspection of the roof. This is typically done by a professional roofing contractor or inspector. They will assess the extent of damage, identify the root causes, and determine the appropriate repair solutions.Commercial buildings can have various types of roofing systems, such as built-up roofing (BUR), single-ply membrane roofing (TPO, PVC, EPDM), modified bitumen roofing, metal roofing, or asphalt shingles. The repair process can vary depending on the type of roof.