Roofing in Swanage

Stone slate repair and relaying. Slipped and broken slates replaced with matched stone, whole slopes stripped and relaid where the fixings have gone. Three rules decide whether it lasts: never alter the pitch, keep the head lap to no more than a third of the slate length and the side lap at 75mm or more, and keep the diminishing courses. We sort as we strip, so sound stone goes back on the elevation facing the street. Torching made good. Nothing pointed. Better than a quarter of the town predates 1919, and on fabric of that age materials have to be matched and the mortar has to be softer than what it beds, so lime rather than cement.

Fixings on the seaward elevations. Not everything is stone. The later streets carry plain clay tile and natural slate, and the post-war stock concrete interlocking tile where the covering is sound and the ridge bedding, verge and underlay are not. Those get screwed down under BS 5534 rather than re-bedded in mortar. The bay faces east, so the elevation taking the salt off a coast little more than a mile away is the one looking at the water, not the one facing the prevailing south westerly. Salt corrodes nails, clips and steel from the edge inwards and keeps a surface damp between showers, so a covering can look sound while what holds it down has gone. Stainless or silicon bronze on those slopes, and since wind works at the edges and the openings rather than the middle of a surface, that is where we specify hardest.

Under any covering sit the battens, the underlay and the rafter feet. Perished felt, soft batten ends and a wet rafter foot at the eaves are what we look for from inside first. Rear additions, dormer tops and bay roofs go in felt, GRP fibreglass or EPDM rubber, with the deck checked before the falls, upstands and outlet. Chimney flashings, soakers, valleys and abutments are renewed in code rated lead. Cast iron rainwater goods are common here and often worth repairing rather than replacing, and with land in the town in flood zone 3 and a high surface water band, a downpipe discharging onto the ground rather than into a drain is worth putting right at the same time.

Moss holds water against a covering and what comes off blocks gutters and valleys, so clearing it is ordinary maintenance. But mossing is a traditional bedding method on stone slate, so moss on a Purbeck roof is not automatically a fault, and we never pressure wash stone. Nearly two in five dwellings in the town are flats or maisonettes, where the roof belongs to the freeholder and comes out of the service charge, so before anything is priced we need to know who can instruct the work. With the covering off, insulation, eaves ventilation and any condensation problem are far cheaper to sort.

No rate per square metre: on a stone roof the covering is rarely what decides it. Purbeck slate that can be lifted, sorted and put back changes the material cost, while delaminated stone has to be replaced, and matched stone is quarried locally, not ordered from a catalogue. Frontages are tight and many roads in the south of town are unadopted, so where a scaffold and skip stand is settled first. work at height rules are why the platform is a priced line. The chain ferry takes no vehicle above twenty tonnes, so heavy loads come through Wareham and Corfe, and we sequence a job so that happens once.

The stone gets the attention, but a large share of dwellings are flats and maisonettes, much of it Victorian and Edwardian guest houses cut into flats rather than purpose built blocks. The roof over a conversion belongs to the freeholder and is managed on their behalf, so the person who rings often cannot authorise the work, and the useful first move is finding out who manages the building.

A converted house also carries a sequence of alterations above it: a flat roof over a rear addition, a dormer added later, lead patched by three different people. Reading that sequence is most of the survey.