Roof leak detection in Ottery St Mary

The centre of Ottery St Mary is a compact, historic knot around the church, Georgian and Victorian frontages on the main streets with cob and thatch survivals tucked into the lanes behind them, and post-war and modern estates spreading out north and west on plainer concrete tile.

Thatch and a concrete tile estate roof fail in almost opposite ways: thatch is a thick, absorbent, self-shedding material where a fault usually means a substantially deteriorated area of coat rather than a single slipped unit, while a modern estate roof more often fails at one discrete point, a ridge, a verge, a flashing, that a thermal pass can isolate cleanly.

Honiton, Sidmouth, Cullompton and Exeter are the nearest towns also covered here, each written up separately because a cob and thatch cottage in the Ottery lanes fails on a completely different timescale to a post-war semi on a Cullompton estate.

Ottery sits on gently rolling ground in the Otter valley between the Blackdown Hills and the coast, sheltered enough that it rarely gets the direct battering a coastal town takes, but the valley floor holds mist and damp readily, so moss and lichen build up fast on shaded slopes and roofs generally take longer to dry out after rain than they would on higher, more open ground.

That slower drying works in a trace's favour: a wet patch under a covering here tends to still be reading differently to its surroundings for longer after rain than it would somewhere more exposed to drying wind, which widens the useful window for booking the flight.

The EX11 postcode area sits inland enough that it rarely shows up in a coastal storm forecast, which can lull an owner into assuming the roof is under less pressure than it actually is once the valley's persistent damp is taken into account.

Opening up a thatch coat to go looking for a leak is expensive and disruptive in a way that opening a few tiles never is, so establishing roughly where the damp is sitting before any physical investigation starts matters more here than almost anywhere else on this site's coverage.

On the newer estates to the north and west, by contrast, the job is usually quicker: a discrete modern roof with straightforward access, where the thermal pass is comparing like against like across a uniform covering rather than reading a historic, textured one.

Cadhay House and the older farmhouses on the town's edge carry some of the most complex historic roofs in this corner of Devon, well beyond the ordinary cob and thatch cottage, and a trace on a building like that is planned with as much care over what cannot be assessed as over what can. The same 48 hour report and fixed price apply, but the write-up says plainly where standing water, thick moss or a plainly obscured section has limited what the flight could confirm.