Drone surveys in Newton Abbot, flown by the surveyor who writes them

Newton Abbot sits about half an hour from Exeter down the A380, which puts it comfortably inside a morning. The town has enough terraced housing of one period, and enough large span commercial roofing on its trading estates, that a visit here often covers more than one address for whoever manages a group of properties.

The racecourse, the estuary and the Bovey basin clay workings sit around the edges, and the ground between them is flat, which is unusual for this part of Devon and makes launch points easy to find. It is one of the more straightforward towns on this list to plan a flight in.

Victorian railway-era terraces exist here in large numbers and they were built in a hurry to a pattern. That is useful. When a hundred houses went up the same way in the same decade, they tend to fail the same way in the same decade, so a fault found on one is worth checking for on the rest of the row.

The ornate town centre of the same period brings a different problem: decorative parapets, deep cornices and hidden gutters behind them. Those parapet gutters are the classic invisible defect. They sit above the ceiling of a shop or an office, they fill with grit and leaf litter over years, and nobody looks in them because there is no way to look in them from the ground.

Beyond that come extensive post-war estates on concrete interlocking tile, substantial modern development at Houghton Barton and Wolborough where the questions are usually about workmanship rather than age, and the trading estates with their large span roofs, rooflights and long parapet runs.

The town sits on the flat floodplain where the Teign becomes tidal, ringed by hills, and mist off the river is a regular feature. Low lying and damp is exactly the recipe for organic growth, and shaded slate here holds moss and lichen readily.

That matters more than it sounds. Moss on an exposed slope is a nuisance. Moss in a valley or behind a parapet is a dam, and a dammed valley on a Victorian terrace pushes water sideways under the slates and into the party wall. On a Newton Abbot survey the valleys and the hidden gutters get looked into specifically, not just photographed in passing.

The town is less wind exposed than the coast, but the estuary funnels easterlies through in winter, which is the direction most of the older detailing was never designed for. Easterly driven rain finds the gaps that thirty years of south westerlies never touched.

The large span roofs on the trading estates are their own category of survey. Profiled sheet with rows of rooflights, long parapet gutters and roof mounted plant, all of it invisible from the yard below. What shows from the air is the whole system at once: which rooflights have gone milky and brittle, where a fixing line has worked loose, whether the gutters are running or standing, and whether the plant has been sitting on the covering long enough to mark it.

For anybody managing one of those units, that overview is usually the point. A roofer quoting off a ladder sees one corner. A single set of aerial frames covers the lot and gives a basis for deciding whether this is a repair year or a replacement conversation.