Drone survey in Liskeard

The Victorian centre was built on copper and tin wealth, and it shows in the scale of the stone and rendered buildings. Substantial townhouses, a public hall and civic buildings, alongside terraced miners' cottages and modern estates on the outskirts.

Big Victorian buildings have big roofs with complicated geometry, and the ones in Liskeard carry Delabole and natural slate with slate hanging on the exposed faces. Those roofs are usually sound in the field and worn at the junctions, which is the pattern across most of this stock.

The town sits high with Bodmin Moor to the north, and rainfall is well above average with driving rain from the south west constant through the winter. Steep valleys on the eastern side add local variation in exposure.

Constant winter driving rain does its work at flashings and abutments, where water is pushed sideways into a joint rather than running past it. Chimney flashings and the junction where a lower roof meets a higher wall are the usual places to look.

The miners' cottages are small, tightly built and often in continuous runs, so the ordinary terrace questions apply: party walls, shared valleys, stacks on boundaries and water crossing from one property to another.

On a continuous run, photographing the whole terrace rather than one house is the practical approach, because a defect three doors along can be the cause of a problem in your own back bedroom.

Outside the centre there is open country in every direction and the Looe valley below, so approaches are easy. Inside it the streets are narrow and the buildings are tall, so take off is planned.

Weather is the usual limiting factor. Conditions here are more like the moor than the coast, which means a wider seasonal spread of unflyable days than at Saltash or Plymouth.

This is former mining country, and around Liskeard that leaves a landscape of old workings, adapted industrial buildings and structures that have been reused for something other than their original purpose. Roofs on converted buildings are frequently a mix of original fabric and later work that meet in awkward ways.

Those junctions are where a survey concentrates. A modern covering meeting a Victorian stone parapet, a new rooflight cut into an old slope, a lean-to added against a wall that was never meant to carry a flashing: each is a place where two different practices have had to be reconciled by somebody on site.

The Looe valley line and the steep eastern valleys also mean some PL14 properties sit well below the general level of the town, which changes both their exposure and where an aircraft can usefully work from.