Can a leaking flat roof be repaired?

A defined split, an open lap, a failed upstand or a defective outlet on a covering that is otherwise sound and flexible. These are straightforward to correct with compatible materials, and the repair should last.

Compatibility matters: patching one system with another rarely bonds properly, and the join becomes the next failure.

Where the covering has become brittle and cracks when handled, where blisters and ripples appear across the roof, where the deck is soft, or where damp continues internally after previous repairs. In those cases the water in the build-up is the problem, and surface work does not remove it.

Persistent ponding is a similar case: repairing a seam that will spend its life underwater buys very little time.

Temporary repair to stop water entering while renewal is planned is entirely sensible, and it should be described as temporary. What is not sensible is a series of temporary repairs presented as maintenance.

Ask what a repair is expected to achieve and for how long. An honest answer may be a season, and that can still be the right decision.

A note of the date, location and nature of each repair, ideally with a photograph of the area before and after, makes the next inspection considerably more useful. Without that record, a new contractor has to guess whether a soft patch is a fresh problem or one that was patched before and has resurfaced.

This matters most where a roof has had several small repairs over the years, because the pattern across those repairs — clustered in one area or scattered across the roof — is itself diagnostic information worth preserving.