Flat roofing in Three Legged Cross

What fails first. On felt it is the creases and the junctions. A three layer built up system with a mineral cap sheet lasts well until the surface goes brittle, then it splits where it has been folded.

On a Three Legged Cross roof, a single torch on layer laid over an older covering blisters, because the damp underneath had nowhere to go. And a lifted or failed seam at an upstand lets water run under the whole roof rather than through one hole, which is why the stain is never where the fault is.

What we lay. EPDM rubber on a plain rectangle, bonded down in a single sheet with no lap or seam in the open field. GRP fibreglass where the roof has kerbs, corners and upstands, because it is laminated in place and the detail becomes part of the same skin. Single ply, hot air welded, on a long run.

Deck, joists and falls. Plywood, OSB or chipboard decking sits on joists, and the firrings on top are what create the fall to the outlet. Wet chipboard swells, gives underfoot and comes off. A roof laid flat holds standing water, and ponding in the same place every winter will shorten a new covering exactly as it shortened the old one. BS 6229 sets out the falls and the drainage, and where re-firring is not practical we build the fall in tapered insulation.

Garden rooms are where this goes wrong. Any heated space in Three Legged Cross brings the insulation into scope under Part L when the covering is renewed. A warm roof puts the PIR above the deck, with a vapour control layer beneath it and the membrane over the top, so nothing in the structure is ever cold enough to condense on. A cold roof puts the insulation between the joists and leaves the boards below the dew point, which is exactly how interstitial condensation gets into a build up and rots it from above. Building control are notified and inspect it before it closes.

Junctions and openings. A small roof with four junctions has more places to fail than a big plain one, so this is where the care goes. The abutment gets a chase cut in and a lead cover flashing dressed home, with a cavity tray above it. A parapet gets a coping and an apron. Openings sit on kerbs so the covering turns up an upstand: rooflights, a lantern, a Velux style flat roof window, a hatch, a soil and vent pipe. The free edges finish on a drip trim, and the rainwater outlet takes the water to a hopper, a downpipe or the gutter. A garden room or an extension is two or three working days, and we say how long first.

We will not quote a rate per square metre. Measuring the area takes a minute. What is under the covering is what decides the job.

How high it is, and where. A garage beside the drive is the simplest set up. A flat roof over a back extension with a conservatory beside it, or a dormer cheek at first floor, needs a bigger platform, and the platform stays up while the deck is open. The work at height rules are the reason access is its own line.

The deck. Three Legged Cross roofs from the seventies and eighties were often decked in chipboard. Once it has been wet it swells and goes soft, and it cannot be re-covered. Sound ply or OSB can. We lift a corner before we quote, because the deck is the biggest unknown in the price.

The falls and the outlet. Plenty of older flat roofs in Three Legged Cross were laid almost dead level, so water sits in the middle. Firrings put the fall back in and send the water to the outlet. That is more work than laying a membrane on top, and it decides how long the new covering lasts.

The system. EPDM rubber, GRP fibreglass and torch-on felt are all sound when laid properly. Each detail at an upstand, a wall abutment or an edge trim takes time, so a small roof with lots of edges can take longer than a big plain one.

Before you choose, ask which system is being quoted, whether the deck is renewed or covered over, and whether firrings are going in to correct the fall.

Three Legged Cross sits inside the green belt. For a repair that means nothing at all: re-covering the garage you already own is maintenance and nobody needs telling. For a new flat roofed garden room, home office or extension it means the size, the height and where it sits on the plot get looked at before anyone thinks about the covering. Some of it falls inside permitted development and some of it will not, and that is worth settling first.

There is a practical side that catches people out. Garden rooms and offices are often bought as a kit and put up with a roof designed to be cheap rather than to last. The fall is token, the outlet is a hole in a corner, and the insulation sits between the joists in a cold build up that condenses the first winter you use it. If you are having one built, get the roof specified as a warm roof with a real fall and a proper outlet from the start. It is a small part of the cost and it decides whether the room is usable in five years.

We cover Three Legged Cross and its closes off Ringwood Road and Verwood Road, along with West Moors and Woodlands, about nine miles out from our base in Boscombe. Planning and building control sit with Dorset Council.

The business is Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719. Thomas Hannen is the owner, and he gets up on every flat roof and works out the price in person. On Checkatrade, a verified customer rated the work 10 out of 10. Coming out to look is free, and the itemised quote in writing is free as well. Before you book a visit in Three Legged Cross, you can read our customers' Google reviews, word for word, on our reviews page.

Most repairs in Three Legged Cross 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.