When is drone inspection more useful than a ladder inspection?

A ladder gives safe access to gutters, eaves details and the lowest part of a slope. Beyond that, on a pitched roof, it gives a view of very little: the ridge, the upper slope, valleys and the far side of a chimney are all out of sight.

Working from a ladder onto a roof is also where most domestic roofing accidents happen, particularly on wet, mossy or fragile coverings.

High, steep, fragile and awkward roofs, whole-elevation coverage, ridges and hips, chimney heads, valleys, box gutters and roof lights. It also suits situations where scaffolding would otherwise be erected purely to look at something.

The dated image set is a second benefit: it gives you a record to compare against in future, and evidence to discuss rather than a verbal description.

Both are visual. Neither establishes the condition of battens, underlay or decking, timber condition inside the structure, or moisture within a flat roof build-up. Those need physical access, roof space inspection or opening up.

A drone survey should say so plainly. Nobody should suggest that flying a roof has ruled out concealed defects, because it cannot.

Strong wind, heavy rain and poor light all reduce the quality and safety of a drone survey, so flights are usually planned for calmer, brighter conditions rather than carried out on demand regardless of weather. Nearby trees, overhead cables and restricted airspace near airports can also limit where and how a drone can be flown safely.

None of this makes drone survey unreliable; it simply means the timing of a flight is chosen deliberately rather than fitted around an emergency.

For most routine inspections of a pitched roof, a drone survey answers the initial question of where to look more quickly and more safely than a ladder ever could. For work that involves lifting a slate, testing a fixing or dressing a flashing, physical access is unavoidable regardless of how good the images are.

A sensible sequence is drone or visual survey first to identify the areas of concern, followed by targeted physical access only where the images cannot settle the question. This sequencing generally reduces the total amount of access equipment needed over the course of a diagnosis, since it is arranged for the specific spots that need it rather than the whole roof by default.