Flat Roofing in Stone

The boards, first. Under the covering you find plywood, OSB, chipboard, or on older work plain boarding across the joists. Chipboard that has taken water swells once and never comes back, and it sags between the joists. Ply that flexes underfoot is going the same way. New OSB is what most of it goes back in, and with the deck open the joists get looked at properly.

Then where the water is meant to go. Plenty of these roofs were laid dead level, or the fall runs at a rainwater outlet that has since been kerbed over. Firrings go over the joists, or tapered insulation does the same job where the roof is built warm, so the surface drains at one point instead of holding a pool. Ponding keeps grit and moss on a cold wet surface and that is where the next split turns up. The hopper, gutter and downpipe get run through before we price the covering.

The edges and the wall behind them. Almost nothing fails out in the middle. It fails at an upstand against the house wall, at a parapet, or along an edge trim whose fixings have worked loose. An abutment takes a lead cover flashing dressed into a chase. A parapet wants its coping bedded and a cavity tray behind it. Every open edge gets a trim with a drip on it. Each junction is priced on its own, because that is where the hours are.

What goes back on. EPDM rubber lays as a single sheet with bonded laps and no flame anywhere, which is the quiet answer over a shared landing. GRP fibreglass is laid wet over new ply and cures as one skin, and it takes foot traffic. Built up felt in three layers under a torch on mineral cap sheet is the toughest walked surface of the lot. Single ply is welded and earns its place on a long garage block rather than a porch.

Insulation, and anything standing up through it. Renew most of a covering and the insulation standard comes with it. A warm roof puts PIR above the deck with the vapour control layer under it, which holds the dew point out of the timber. A cold roof keeps insulation between the joists and has to be ventilated, or condensation and interstitial damp quietly rot the boards with nothing showing on top. BS 6229 covers the build up and Approved Document L the standard it has to reach. A rooflight, a lantern, a Velux, a hatch, a soil pipe or a vent pipe gets a kerb built up or a collar formed round it, never a bead of sealant.

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 garage in a block, a canopy over a communal entrance and a two storey rear extension are three different jobs before any covering 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 Stone, Pamphill, Wimborne Minster, Furzehill and Merley across BH21, 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.