Flat roofing in Langton Matravers

The roof over the back. Most stone houses here have gained a single storey addition at some point, and it nearly always has a flat top. Where the deck is sound we strip to the boards and lay EPDM rubber, which goes down as one sheet with bonded seams and very little to fail, or GRP fibreglass where there are kerbs, steps and awkward corners to work round. A torch on torch on felt, three layers under a mineral cap sheet, still has its place on a larger, plainer roof.

Garages, stores and workshops. Detached buildings weather from every side and have nothing warming them, so the covering hardens sooner. Single ply, welded at the laps, suits the bigger spans. Whatever goes on, the deck comes first: plywood, OSB or chipboard, and chipboard that has been damp for a season has to come off.

Junctions with rubble stone. This is the part that makes local flat roofing different. A rubble stone wall does not give you a clean line to cut a chase into, so an abutment is formed by taking a lead cover flashing into a raked bed joint and wedging it, rather than grinding a slot across the face of the stone. Where there is a parapet the coping and any cavity tray matter as much as the membrane. Get this wrong and the roof is blamed for a wall that is letting water in.

Falls, insulation and the damp that is not a leak. Firrings give a flat roof its falls, and without them you get ponding and standing water at every low spot, which works on every lap and seam it sits over. Tapered insulation corrects a fall from above where headroom is tight. A warm roof puts PIR over the deck on top of a vapour control layer, keeping the timber warm enough never to reach the dew point. A cold roof leaves the insulation between the joists and has to be ventilated, or condensation and interstitial damp rot the decking with no rain involved. BS 6229 is the code both come from.

Edges, openings and rainwater. The usual faults are blisters and bubbles, a split or crack in a tired covering, and a lifted or failed seam. At the perimeter it is the edge trim, the drip and the apron. Openings mean a rooflight, a lantern or a Velux on a formed kerb, and any soil pipe or vent pipe. Then the rainwater outlet, whatever hopper it drops into, and the downpipe below, with fixings and trims chosen to survive the salt that reaches this far.

No rate per square metre, because the square metres are the easy part and what is under the covering is what decides the job.

Getting to it. A stone cottage extension with no side access, a garage off a narrow lane and a porch roof over a doorway are three different propositions before a board is lifted. A garage or a single storey extension will often come off a tower, anything above a two storey wall wants a scaffold, and the platform has to stand while the deck is open rather than for an afternoon. The work at height rules are why it is a priced line rather than something folded into a rate.

The deck under the covering. A sound deck can be re-covered. Chipboard that has been wet for years, or ply that gives underfoot, has to come off and be replaced, and you cannot tell which you have from the ground or from a photograph. We lift a corner before quoting, because the deck is the single biggest swing in the price.

The falls, and where the water is meant to go. Most flat roofs that fail were never laid to a fall, or the fall runs at an outlet that has since been blocked or built over. Correcting it with firrings is more work than laying a membrane and it is the difference between a roof that lasts and one that ponds. Upstands, edge trims and each outlet are priced one at a time, because that is where the hours and the leaks both are.

Comparing quotes? Ask which system is being quoted and how many layers, whether the deck is being renewed or covered over, whether the falls are being corrected with firrings, how the upstands, outlets and edge trims are detailed, and whether the scaffold and the skip are in the price. Two quotes for the same job are usually two different jobs.

We cover Langton Matravers, Acton, Kingston and the BH19 addresses along the ridge towards Swanage, with Dorset Council as the planning authority. You are dealing with Bournemouth Roofing & Building, the trading name of Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, which you can look up in a minute. Thomas Hannen's business, and he is the one who comes out to price the job, not a salesman. A verified customer's 10 out of 10 on Checkatrade. The visit and the written quote are both free.