Flat Roofing in Corfe Mullen

First to go are the trims. An edge trim is a length of metal or plastic with a drip formed into it, holding the perimeter of the covering down and throwing water clear of the fascia. Fixings work loose, the joint between two lengths opens up, and water starts running back underneath instead of falling off the end. Replacing them is half a day and it saves the roof.

Next is the junction with the house. Wherever a flat roof meets a wall, the covering has to turn up as an upstand and something has to cap it. On the newer estates that is a cover flashing cut into a chase; on anything older it is lead worked over an apron. Mortar shrinks out of a chase, lead splits along a fold, and a parapet loses the bedding under its coping or never had a cavity tray behind it to start with. All of that is edge work and none of it means a new roof.

Then the outlet. It is the lowest point on the roof and everything ends up there, so it silts, and once it silts the roof holds water. Standing water is the accelerator: it works into a lap, lifts the seam and gets in underneath. We clear the outlet, the hopper, the gutter and the downpipe as a matter of course, and where a roof has always ponded we take the boarding up and re-cut the fall with firrings or tapered insulation so it drains where it was meant to.

The covering itself usually goes last, and it announces itself first. The mineral finish wears bald, blisters and bubbles lift, and the surface cracks wherever a thumb presses. One split is a repair: back to sound material, a new piece welded or bonded across it, the edge dressed flat. A dozen splits is a re-cover. What goes down then is EPDM as one cold bonded rubber sheet, GRP brushed on wet over new plywood and cured as a single fibreglass skin, three layer built up felt under a torched mineral cap sheet where the roof gets walked, or welded single ply across a wide span. Rooflights and lanterns come off and go back on kerbs we build up so the skylight sits above any standing water, and Velux units, loft hatches, soil pipes and vent pipes each take a collar.

And underneath everything, the deck. Chipboard was standard on this era of extension and it does not survive damp, so once it goes soft at a corner it comes out and OSB goes down instead. The joists get looked at while the boards are up. If most of the covering is coming off anyway then the insulation standard is engaged, and the sensible build is warm: PIR above the deck with the vapour control layer under it, keeping the dew point out of the timber, rather than a cold roof depending on a ventilation gap nobody is ever going to inspect again. BS 6229 sets out the construction and regulation 23 of the Building Regulations is what brings insulation into it when a covering is renewed.

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 detached garage at the end of a drive, a sun lounge across the back of a bungalow and a two storey rear extension are three different jobs before anything is unrolled. 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 Corfe Mullen, Broadstone, Merley, Upton and Lytchett Matravers across BH21 and BH16, out from Bournemouth. 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.