Drone survey in Okehampton

Dartmoor forces Atlantic air upwards immediately south of the town, so rainfall is high, driving rain is frequent and roofs stay wet for long periods. This is about as demanding a climate for a building as anywhere in the coverage area.

Driving rain is different from ordinary rain in what it does. It is pushed at vertical and near-vertical surfaces and up under laps and flashings rather than running down. Details that would be adequate in Taunton are not adequate here, which is why local building practice uses more slate hanging, deeper laps and heavier bedding.

The town centre is granite and slate with Victorian terraces around it, a large stock of post-war housing, and scattered moorland farms and longhouses in the surrounding parishes. Granite-bedded ridges are a local detail and a durable one.

The farms are a distinct kind of work: corrugated metal on the sheds, slate or metal on the houses, and buildings that are frequently a long way from any road. Those are ideal for aerial survey because reaching them with equipment is the expensive part.

Wind is the constraint. Moor edge conditions can change quickly and a day that starts calm in the town can be unflyable an hour later as cloud comes over the high ground. Jobs here are booked to a window and confirmed on the morning.

Space is not a problem. There is open ground everywhere, and the difficulty is the weather rather than the geography or the airspace.

Prolonged wetting rather than dramatic damage. Growth in the laps, saturated timber at the eaves, mortar that has gone soft, and the slow opening of laps and flashings under driving rain. Individually minor, collectively expensive if left.

For the farms it is usually about deciding which of six buildings needs work first, which is a question a set of photographs answers in an afternoon and a walk round the yard does not.

Okehampton Castle, Meldon Viaduct and the older stone buildings of the town are all built from and for this landscape, with heavy materials and details designed to shed a lot of water quickly. That approach carried into the domestic stock, and it is why local roofs look heavier than their equivalents further east.

For an EX20 owner the useful point is that those details need maintaining rather than admiring. Granite-bedded ridges and deep laps work extremely well while the bedding is sound and fail properly once it is not, and the transition between the two states is not gradual.

The moor itself is close enough that a property on the southern edge of the town is in a different climate from one on the northern side, which is worth saying plainly to anybody comparing quotes with a neighbour.