The surface defect and the wet area can differ
Water entering through a seam or curb detail can spread below the membrane. The leak visible inside might be small while the affected insulation extends farther. An assessment needs to consider the assembly below, not only the opening on top.
Moisture affects performance and can conceal deterioration at fasteners or the deck. A coating does not dry that assembly or replace damaged support. The extent and condition of affected material shape whether localized removal or wider replacement is needed.
