Flat roofing in Longham

What comes off. Felt, in almost every case. A three layer built up system finished with a mineral cap sheet, or a single torch on layer laid over the previous one to buy a few years. It fails the same way each time: splits along the creases, blisters where damp was shut in underneath, and a lifted seam where the covering turns up an upstand. A failed seam lets water travel under the whole roof, which is why the stain never appears where the hole is.

What goes on. EPDM rubber on a plain rectangle, bonded down in one sheet so there is no lap and no seam in the open part of the roof. GRP fibreglass where there are kerbs and upstands to laminate round, or where the roof will be walked on. Single ply, hot air welded, on a long run over an extension.

Decking, joists and falls. Under the covering is plywood, OSB or chipboard. Chipboard that has been damp for a season swells and gives underfoot and has to come off. The joists usually survive, and the firrings sitting on them create the fall to the outlet. A roof laid dead flat holds standing water, and that ponding shortens a covering more than any storm does. Where re-firring will not work we build the fall in tapered insulation. BS 6229 is where the falls and the drainage come from.

Condensation is not a leak, and it is more common than one. Where a room below is heated, Part L brings the insulation up when the covering is renewed. We build a warm roof, which puts the PIR above the deck with a vapour control layer under it and the membrane over the top. The old way, insulation stuffed between the joists, is a cold roof: the boards sit below the dew point, moist air from the room finds them, and interstitial condensation soaks them from above while the outside stays perfectly dry. Building control are notified and inspect it.

Edges, junctions and openings. Where the roof runs into the house we rake out a chase, dress lead into it as a cover flashing and set a cavity tray over the top. A parapet takes a coping with an apron beneath. Everything that comes through the covering is raised on a kerb first, so the membrane can turn up an upstand: rooflights, a kitchen lantern, a Velux style flat roof window, a hatch, a soil and vent pipe. The open sides finish over a drip trim, and the rainwater outlet takes it all to a hopper, a downpipe or the gutter. A garage is a day, an extension two or three working days, and we say how long first.

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 bungalow garage, a flat link roof between house and garage, and a wide extension across the back of a detached house are three different jobs before anything 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.

Longham is bungalow country, and a bungalow changes the arithmetic of a flat roof in two directions at once. There is more roof for the same floor area, so a greater share of what you pay to heat the place goes straight up through it. But everything is at single storey height, which usually means a tower rather than a full scaffold, and the platform stands for days rather than weeks.

The practical upshot is that a warm roof build up is better value on a bungalow than on almost anything else. While the covering is off and the deck is open, adding the vapour control layer and PIR above it costs a fraction of what it would as a separate job, and on a bungalow you feel the difference in the room below. If you are having a garage, a link roof or a back extension re-covered anyway, ask us to price the warm build up alongside the plain one. Sometimes it is worth it and sometimes it is not, and you should see both numbers before you choose.

We cover Longham, Ferndown, West Parley, Hampreston and the rest of BH22. 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.