Flat Roofing in West Moors

The joists. We start at the bottom. Bungalow flat roofs on this side of town are framed in light timber, and the ends resting on the wall plate soften first, because that is where a wet deck has been sitting on them. Every one gets prodded once the boarding is off. Most of the time the ends want packing or a fresh length sistered alongside, which is an hour. Where timber has gone spongy along its length we stop and tell you, because bonding a new covering onto a frame that is finished helps nobody.

The boarding. Chipboard was the cheap deck of its day and water destroys it, so once a corner crumbles between finger and thumb the sheet is done. Plywood survives longer but comes apart in layers, and you feel that flex under your heel before you see it. Either way it lifts out and OSB goes down in its place, screwed rather than nailed so it cannot work loose. Dry, firm boards we leave alone, and that single decision swings the quote further than any other.

The fall. Nothing here is truly flat, or it ought not to be. Firrings are tapered lengths of timber that sit along the joists and tilt the whole deck towards the outlet. Where a roof holds water, either firrings were never fitted or they run the wrong way across it. We re-cut them, or lay tapered insulation to do the same job, and we put the outlet at the genuine low point instead of wherever the last man found convenient. The hopper, gutter and downpipe below it get rodded through at the same time, because a blocked rainwater run will drown a covering that had years left in it.

The covering. Then it is a choice between four. EPDM comes off the roll as one piece of rubber, bonds down cold and puts no flame anywhere near a bungalow soffit, which is why it ends up on most garages and porch canopies. GRP is brushed on wet across fresh plywood and hardens into a single fibreglass skin with the trims formed as part of it. Built up felt, three layers with the mineral cap sheet torched on last, is still the toughest surface to walk about on. Single ply is hot air welded at every lap and earns its keep across a wide open span. Blisters, bubbles, splits and a lap that has peeled back are all patchable in any of them: we go back to material with life in it, weld or bond a new piece across, and dress the edge down flat.

The insulation, and then the edges. If the covering is coming off anyway, that is the moment to settle warm roof against cold roof. Warm means PIR board above the deck with the vapour control layer beneath it, so the timber sits on the dry side of the dew point. Cold means insulation left between the joists with a ventilated gap over it, and when that gap gets blocked the condensation goes quietly into the boards where nobody will look for it. BS 6229 covers how the build should go together and Approved Document F the ventilation. The edges go on last and they are what keeps you dry: a cover flashing chased into the house wall or lead worked over an apron on an older detail, coping re-bedded on a parapet with a cavity tray behind it, a drip trim down every open side, and a kerb built up under any rooflight or lantern so the skylight stands above standing water rather than in it. Velux units, loft hatches, soil pipes and vent pipes each take a collar.

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 sun lounge across the back of a bungalow, a detached garage down a side drive and a flat link between two pitched roofs 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 West Moors, Ferndown, Three Legged Cross, Ashley Heath and West Parley across BH22, 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.