Can a drone inspect a flat roof properly?

A plan view of the whole roof, which is exactly what a flat roof needs: where water stands, how debris is distributed, whether outlets are clear, and how the surface differs across the area. Ponding is far easier to judge from above than from the edge.

Close imagery of upstands, kerbs, roof lights, outlets and edge trims completes the visible picture, with dated images to compare against later.

Whether insulation or decking beneath the covering is wet. Whether the deck is firm. Whether a blister contains water. These require walking the roof, probing, a core sample or a moisture survey.

Nobody should present drone imagery as evidence that a flat roof build-up is dry. It cannot show that, and saying otherwise would be misleading.

The survey identifies where the problems are and where testing should be concentrated, which keeps physical investigation targeted. On inaccessible roofs it is often the only way to see the surface at all without erecting access.

Drone imagery is weather-dependent in its own right: strong wind, rain or poor light limit what can be captured safely and clearly, so a survey sometimes needs rescheduling rather than being flown regardless of conditions. Even good imagery cannot replace the physical steps that follow it, such as probing a soft area, walking sections rated for foot traffic, or extracting a core sample from a suspect part of the build-up.

Treat the drone survey as the step that decides where physical testing should be concentrated, rather than as a substitute for it. A roof identified from imagery as having widespread blistering still needs someone on site to establish what is actually happening beneath the surface, and a written report should say plainly which of its findings come from imagery and which from direct testing.