Flat roofing in Wool

A repair. One thing has failed and the rest of the roof is sound: a split at an upstand, a blister standing off the boards, a trim worked loose, a lap opened at a corner, an outlet packed with grit. Felt is cut back, primed and welded in under a fresh cap sheet. GRP fibreglass is ground out at the crack and laminated again. EPDM rubber is cleaned and bonded down. Hours rather than days, and worth having while the rest of the surface still bends. The only test that matters is whether the deck under the fault is dry.

The edges, without the middle. Most people do not know this one exists, and on roofs of this age it is often the right answer. The field of the covering is still sound but everything around it has gone: the edge trim and its drip, the apron at the front, the upstand where the flat meets the house, the coping on a parapet and the cavity tray behind it, the kerb round a rooflight. We renew that perimeter, weld or bond the covering back into it, and leave a surface that still has years in it doing the job it is doing.

The full job, down to the joists. Where the deck has gone there is no shortcut. Chipboard decking that has been wet loses its strength and sags between the joists, so it comes off and new boards go down. Plywood or OSB that has stayed dry takes a covering without argument. The falls are then rebuilt so the roof drains at an outlet, to the fall BS 6229 sets out, because standing water forces itself into every lap and seam and a frost then splits them apart. Roofs of this vintage are cold roofs, insulation between the joists with a dead void above it, which is where condensation gathers and interstitial damp rots the deck without a mark showing on top. Built back warm, the PIR goes on top of the deck and the vapour control layer underneath, and no cold void is left at all. The covering goes on last: EPDM rubber in one sheet, GRP fibreglass, a new three layer torch on system, or single ply hot air welded on a long straight roof.

The things that come up through it. A rooflight, a lantern, a Velux, an access hatch or a soil and vent pipe each want their own kerb and collar rather than a bead of sealant. Where the flat runs into brickwork a lead cover flashing is chased in, cut so it can move without tearing. Then the gutter, the hopper and the downpipe below are cleared and run through, because a full outlet and a finished covering look identical from indoors.

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 on a village plot, a kitchen extension against the back of the house, and a flat topped dormer above a bedroom are three different jobs before anything is stripped. 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.

Better than half the housing here went up between the war and the early eighties, most of it in the seventies. The flat roofs went on within a few years of one another and they are reaching the end on the same timetable. It is why one street can have four garages leaking in the same winter, and why the fault is nearly always the same fault: trims, upstands and outlets rather than the covering itself.

That is worth knowing for two reasons. It usually means a smaller job than you feared, because renewing a perimeter is not the same thing as re-covering a roof. And it means a neighbour's quote is a fair guide to your own, which very rarely happens in this trade. Where several roofs on one street need doing we would rather look at them on the same day and price them together, since the access and the waste are the parts that share. The older core of the village is a conservation area, so on a roof that shows from a road it is worth checking with Dorset Council before you change a colour or a material.

We cover Wool, East Burton, Bovington, Winfrith and the villages across west Purbeck, 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.