Drone services in Tiverton

Tiverton is built where the Lowman joins the Exe, and the residential streets climb hard north and west out of a low town centre. That gradient does two things. It puts a great many roofs above the general roofline, where wind loading is higher than the sheltered position of the town would suggest, and it makes conventional access awkward and expensive on the steeper streets.

A tower or a scaffold on a sloping street needs levelling, needs space and often needs the pavement. Photographing the roof instead removes all three problems, which is why so much of the work here is aerial rather than physical even when nothing is urgent.

It also changes what the photographs need to show. On a level street a roof can be understood from two or three angles; on a hill the same roof needs the flight to work around the gradient, because the slope above it hides one elevation completely and the slope below exaggerates another.

The Victorian mill workers' terraces are the characteristic stock, and terraces of that period share more than they look like they do: valleys, party wall abutments and long unbroken runs of slate where one failure travels along the row.

Photographs make ownership arguments shorter. When the water is coming in at the boundary between two houses, a picture showing which side of the valley has failed is worth more than two opinions from two ladders.

The Exe valley here is notably wet even by Devon standards, and prolonged wetting rather than dramatic storm damage is the main agent of decay. Slate that never dries out holds growth, mortar softens, and the failure is gradual enough that nobody notices until a ceiling does.

What that means for a survey is that the useful findings are usually not spectacular. They are a line of moss along one course, a hairline in a flaunching joint, a gutter running slightly the wrong way. All of them are cheap now and none of them is cheap later.

Guttering carries more here than it does in a dry town. A gutter that runs slightly the wrong way is a nuisance in Dorset and a genuine problem in the Exe valley, where it will be full for weeks at a time, and that shows up clearly from directly overhead.

Around the town there is a heavier concentration of historic and institutional property than a market town usually carries: the castle, the school, Knightshayes and the Grand Western Canal corridor, all of which come with complex roofs, lead work and a conservation interest.

That stock generates a different kind of enquiry again, often a condition record ahead of a repair programme rather than a reaction to a leak, and often with somebody else, a trustee or an agent, needing to see the same evidence.