Can a flat roof be repaired instead of replaced?
Yes, when the defect is localised and the surrounding covering and deck remain sound. Replacement becomes more attractive when there are multiple leaks, widespread deterioration, soft or damaged decking, persistent ponding or a history of repeated patch repairs.
When repair is realistic
A single split, a failed detail at an upstand or a damaged area around an outlet can often be repaired, provided the rest of the covering and the deck beneath it are sound.
The deck is the deciding factor. Where water has been getting in for a long period, the boards or timbers below may be soft, and covering that over rarely lasts.
When replacement is the better decision
Widespread blistering, multiple splits, brittle surfacing and repeated failures in different places usually mean the covering has reached the end of its service life.
At that point, repairs become a sequence of short-term fixes, and replacing the covering with the falls and details corrected is the more economical route.