Flat roofing in Sandford

Garages, porches and the extension across the back. The flat roofs here are the ones that came with the house or shortly after it: an attached garage, a canopy porch, a utility or dining room built across the back, and a fair number of flat topped dormers. Most are felt built up in three layers with a mineral cap sheet on top, or torch on felt laid over the top of it later, with GRP fibreglass on the ones done more recently. We open a bay and look at the deck first, every time. Plywood or OSB that has stayed dry can take a new covering as it is. Chipboard decking that has been wet loses its grip on the screws and sags between the joists, and new boards go down before anything else. The covering after that is EPDM rubber, fibreglass, a fresh torch on system, or single ply where the run is long and simple.

Falls, outlets and standing water. Ponding is the fault we are shown most often. Water that stays on the surface finds every lap and seam, and a hard frost levers them open. It is nearly always one of three things: the fall was never built in, the firrings were cut too shallow, or the rainwater outlet has silted up. We rebuild the falls with firrings or tapered insulation so the roof drains at an outlet, which is what BS 6229:2025 on flat roofs expects, then run water through and watch the gutter, hopper and downpipe clear it.

Trims, upstands and seams. A flat roof almost never fails in the field. It goes at the edge trim, the drip, the apron flashing where it meets the house, the kerb round an opening, and the laps. On felt that is a blister, a bubble or a split. On single ply it is a lifted or failed seam. On fibreglass it is a crack at a sharp internal angle. The failed material is cut out, the upstand is rebuilt behind the covering at a workable height, and each seam is welded or bonded rather than sealed and hoped over.

Openings, abutments and the build up. Rooflights, lanterns, a Velux, an access hatch and any soil and vent pipe get a kerb and a collar rather than a bead of sealant. Against brickwork a lead cover flashing is chased into the wall and dressed down over the upstand. On a parapet we check the coping and whether there is a cavity tray behind it. Roofs of this vintage are cold roofs, with insulation between the joists and a void above that was supposed to breathe, and that void is where condensation gathers and interstitial damp rots the deck from below. Rebuilding it warm moves the insulation on top of the boards, over a vapour control layer, and takes the cold void out of the roof altogether.

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. An attached garage beside a driveway, a rear extension on an estate house, and a flat topped dormer above a bedroom are three different jobs before a sheet comes off. 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.

Most of the housing around Sandford went up between the late nineteen sixties and the early seventies, which means the flat roofs on the garages and back extensions all started life within a few years of each other. They have aged the same way too. The felt in the middle of those roofs is often still doing its job, while the timber edge fillets, the verge and the old metal trims have gone completely.

That is worth knowing before you accept a quote for a whole new roof. On a good many of these the honest answer is edge work rather than a re-cover: strip the perimeter back, renew the fillet and the trim, redo the apron where it meets the wall, and let the sound part of the covering carry on. Where the deck has gone soft, or the covering has been over-coated twice already, then it does need stripping and we will say so. Either way, ask any quote you get which of those two jobs it is pricing, because on this kind of roof they are a long way apart.

We cover Sandford, Holton Heath, Organford, Wareham and the villages around them, along with the rest of BH20, and the site visit and quote are both free. 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.