Cambridge Roofers installs and repairs flat roofs in Royston, and this page sets out honest, realistic cost information so you can budget properly before getting quotes.
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Flat roofing prices vary considerably, and quotes for the same roof from different contractors can be surprisingly far apart. Some of that variation reflects genuine differences in specification and material quality. Some of it reflects corners being cut. Understanding what drives the cost of a flat roofing job puts you in a much better position to compare quotes meaningfully.
We install EPDM rubber and torch-on felt systems on extensions, garages, outbuildings, and larger flat roof areas on residential properties.
Flat roof replacement in the UK currently costs, as a broad guide:
These figures include stripping the old membrane, supplying and installing the new system, edge trims, and standard detailing at upstands and flashings. They do not include scaffolding (where needed) or deck replacement, which are priced separately.
To put those figures in context with typical roof sizes:
These are working ranges, not fixed prices. Your actual quote will depend on the specifics of the job. Use these figures to identify quotes that are significantly lower than expected and ask what has been excluded to achieve that price.
Several factors can increase the cost of a flat roofing job above the base rate. Some of these are visible before work starts; others only become clear once the old membrane is stripped.
The single biggest source of unexpected cost on a flat roof job is a deck that is in worse condition than it looked from the surface. Timber decks (plywood or OSB on joists) absorb moisture when a membrane fails slowly over a long period. By the time the leak becomes obvious inside the building, sections of deck may be soft, delaminated, or structurally compromised.
Deck replacement typically adds £30-£60 per square metre for the affected area. On a 20 square metre roof where half the deck needs replacing, that could add £300-£600 to the total cost. In severe cases where most of the deck needs to come out, the additional cost can be significant. This is why a thorough survey - with the surveyor actually on the roof, pressing and checking - matters before any price is agreed.
A flat roof must drain. If the falls across the existing roof are too shallow (less than 1:80), water ponds on the surface and accelerates membrane failure. Correcting falls with tapered insulation boards adds material and labour cost but is the right thing to do rather than laying a new membrane on a roof that will hold water.
Tapered insulation for fall correction typically adds £15-£35 per square metre depending on the depth of taper required. On a small garage roof this may be a modest addition; on a larger or more complex area it adds up.
A straightforward rectangular roof with one outlet is the easiest and cheapest shape to work with. L-shaped roofs, roofs with internal corners, multiple outlets, rooflights, or projecting structures all add cutting and detailing time. More joints and more internal corners mean more potential failure points and more care required at each one.
Where a flat roof meets a wall, chimney, or parapet, a flashing is required. Lead is the most durable and widely used material for this. Lead work takes time - it must be cut, dressed into the wall chase, and overlapped correctly onto the membrane. On a roof with a long parapet wall on two or three sides, the lead flashing cost can be a meaningful part of the total job price.
Most single-storey flat roofs can be accessed safely from ladders. Where a flat roof is above a two-storey extension, or where the working area is over a conservatory or other structure that makes ladder access impractical, scaffolding may be required.
Older flat roofs are often cold roofs, with insulation sitting between the joists below the deck. This arrangement can cause condensation on the cold upper face of the deck, gradually deteriorating the structure from inside. Converting to a warm roof - where insulation goes above the deck, under the membrane - eliminates this risk and improves thermal performance. The conversion adds insulation board cost and slightly raises the finished roof height, but it is often worth considering during a full replacement.
Not every job has complications. Several factors make a flat roof job more straightforward and keep costs closer to the base rate.
A patch repair to a flat roof typically costs £150-£400 for localised work - a split seam, a lifted flashing, a failed outlet collar. This makes clear financial sense if the membrane overall is sound and the damage is genuinely isolated.
If the membrane is over 15 years old and showing widespread surface cracking, blistering, or general loss of flexibility, patch repairs are usually a short-term solution that delays rather than avoids a full replacement. Spending £300 on a patch this year and another £300 next year on a different failure, before replacing the whole roof in year three, is often more expensive in total than a replacement would have been from the start.
A good roofer will tell you honestly which situation you are in. If the membrane is genuinely at end of life, a repair recommendation that avoids that conversation is not in your interest.
When comparing quotes for flat roofing in Royston, check that each quote covers the same scope. Key questions to ask:
A quote that strips, surveys the deck, installs a quality EPDM system with properly detailed flashings, and removes all waste is genuinely better value than a cheaper quote that lays over the existing membrane and leaves deck condition as an unknown.
If you are planning a flat roof replacement or want to understand the realistic cost of repairing your existing roof, call Cambridge Roofers to arrange a survey. We will assess the roof properly, explain what we find, and give you a clear, itemised picture of what the work involves.
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Call any time. Calls are answered day and night and passed straight to our roofers.
