Roofing in Furzehill

Ridge and verge, in mortar. The default detail on every roof of this vintage and the first thing to fail. Ridge tiles bedded in sand and cement crack along the joint, water gets behind, and the bedding lets go in pieces. Gable verges here almost all sit on a mortar undercloak that drops off in slabs. We strip the mortar and convert to dry ridge and dry verge screwed onto a ventilated roll, which is the mechanical fixing BS 5534 expects and vents the roof space along the ridge while it is at it. Nearly half the dwellings went up between 1945 and 1982, most of them in the late sixties and early seventies, and that stock is concrete interlocking tile laid to a shallow pitch, which is fine until a single tile lifts. The older properties towards Holt carry plain tile, clay tile and natural slate on battens with no sarking behind them. Stone slate is a Purbeck thing and you will not find it this side of Wimborne.

Never put a saw through a trussed rafter. Roofs of this era are almost all trussed rafter, a factory made web of thin timbers that only works as a whole. Cutting one for a loft ladder, a tank platform or extra headroom takes the strength out of it. If you want a boarded loft or a room up there, that is an engineer's drawing and new structure, not a saw, and we will say so rather than quietly do it. The other hidden fault on a seventies roof is the underlay at the eaves: the original bitumen has gone brittle and tears exactly where it laps into the gutter, the one place it has to be sound, which is what soaks a fascia with no tile out of place anywhere.

When nails, battens and membrane have gone together the covering comes off, soft timber and rafter feet are replaced, and it goes back on breathable membrane and treated battens with ridges and hips screwed rather than bedded. The integral garage, porch canopy and rear extension are felt, GRP fibreglass or EPDM rubber, deck checked before the falls, upstands and outlet. Cement fillets instead of lead are common here and they all crack, so they come out and code rated lead goes in. The ground here is cohesive and holds water, so where a downpipe discharges is a structural question as well as a damp one. With the covering off, insulation and eaves ventilation are far cheaper to put right, and Approved Document L sets the standard a renovated roof is expected to reach.

Plots here are generous, so there is usually room for a scaffold and a lorry, but the ground is cohesive and it holds water. After a wet spell a scaffold wants sole boards and a skip wants boarding out, or you buy yourself a rutted lawn along with a roof. How long a platform stands matters as much as its size, and the work at height rules are why it goes on the quote as its own line rather than an optional extra. Ask whether the scaffold is in it, whether battens and membrane are renewed or covered over, and who takes the old tiles away.

The ground around Furzehill is cohesive and it shrinks and swells with the seasons. That turns a bit of roof drainage from a damp nuisance into something structural, because water repeatedly soaking into clay beside a foundation, or repeatedly being taken away from it, is what moves a wall.

So on this ground we do not treat the gutter as an afterthought at the end of a roof job. A downpipe has to discharge into something that carries water away from the building, not onto a flowerbed against the wall and not into a gully that has silted up.

A soakaway needs to be a sensible distance from the house and it has to pass a percolation test, which on this ground plenty of them do not, so a positive connection to a drain is often the honest answer. Approved Document H covers where the water is allowed to go.

The practical version: have the rainwater goods and the gullies looked at in the same visit as the roof, while the scaffold is already up.