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.

Nobody can honestly price a flat roof by the square metre from the drive. The size is the simple part.

What the felt is sitting on. Garage and extension roofs put up in Longham in the sixties and seventies were commonly decked in chipboard. Chipboard that has drunk rain swells, crumbles at the edges and will not hold a new covering, so Thomas cuts a small inspection hole or lifts a corner before writing anything down. Whether that deck stays or goes is the largest single swing in the price.

Getting the rain off. A lot of older garage roofs in Longham were laid almost flat, or were set to drain to an outlet later boxed in by an extension. Tapered firrings nailed over the joists give the new membrane a proper slope, and that timber and labour is a line of its own. Where the roof meets a wall, each upstand, each run of edge trim and each outlet is costed one by one, since those joins are where water finds its way in.

Which covering. EPDM rubber sheet, GRP fibreglass and torch-on felt each have their own cost and lifespan. A narrow link roof squeezed between house and garage often suits one, and a wide rear extension another.

Height. Over a Longham bungalow garage, a tower does the job. Over a two storey wall, scaffold goes up and stays up until the new membrane is sealed, and the work at height rules are the reason it appears as a separate cost.

So ask any other roofer: will the deck be renewed or covered over? Are firrings going in to fix the fall? Are the skip and the scaffold in the figure?

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.

Bournemouth Roofing & Building Ltd works from a base in Boscombe, 4.7 miles away, and covers Longham, Hampreston, Ferndown and West Parley, all under Dorset Council. The company is registered in England and Wales under number 15471719, and you can check that on Companies House. Before you book a visit in Longham, you can read our customers' Google reviews, word for word, on our reviews page.

Thomas Hannen owns it. He is the person who climbs up to look at your flat roof and writes the price. A verified customer rated us 10 out of 10 on Checkatrade. Neither the visit nor the itemised written quote costs you anything.

Most repairs in Longham need no application at all. What decides whether a change to the outside of your house does is who the council is, whether a conservation area or a listing applies, and whether the place sits in a protected landscape.