Drone roof survey in Cullompton

Cullompton has a sharper split than most Devon towns. The old centre along Fore Street is medieval and Georgian with a significant amount of thatch and cob in the surrounding lanes, and around it sits a very large volume of late twentieth century estate housing, almost all of it concrete interlocking tile.

The two need completely different surveys. On thatch the whole question is the ridge, the coat wear and any vermin damage, and none of that can be assessed from the ground. On a 1990s estate roof the question is mortar bedding, ridge and verge fixing, and whether the tiles have started to rock.

There is a third category worth noting: barn conversions and former agricultural buildings on the edge of town, which often combine original stone or slate with modern materials introduced during conversion, and the junction between the two is where they leak.

The town sits low in the Culm valley, which makes it damp and frost prone. Cold air drains down into the valley overnight, so Cullompton gets frost when the surrounding higher ground does not, and it gets it more often.

Freeze and thaw on wet mortar is one of the most effective ways of taking a roof apart. Water gets into a mortar joint, freezes, expands and opens the joint a fraction, and the following night it does it again. Over fifteen winters the bedding on a ridge line goes from solid to crumbly, and after that the wind does the rest.

Thatch on the valley floor also stays wetter for longer than thatch on a hillside, which shortens the working life of a ridge noticeably.

There is an assumption that a roof built in the last thirty years does not need looking at. In practice, estate roofs from the 1980s and 1990s are exactly the age where mortar bedded ridges start to let go, and a lot of them were built before dry ridge systems became standard.

The other recurring find on estate housing is workmanship rather than age: a verge that was never properly bedded, a flashing that was cut short at a first floor abutment, or a rooflight installed into a later extension without the correct upstand. Those do not fail for a decade and then fail permanently.

Cullompton also has a good deal of profiled metal sheet on its industrial estates, where the failure is corroded fixings and lifted sheets rather than anything to do with tiles.

Cullompton's position at junction 28 of the M5 also means a good deal of roadside commercial roofing has gone up around the town in the last two decades, alongside the historic core. Large flat and low pitch roofs on units built for logistics and retail age quickly under UV and standing water if nobody is checking them, and from ground level a warehouse roof might as well not exist.