How much does a new flat roof cost?
MyJobQuote's flat roof replacement cost guide, updated 12 August 2026, puts the average new flat roof at £2,400 and the 2026 range at £1,500 to £6,000. On a single garage of 15 square metres it gives felt at £1,200 to £1,800, rubber at £1,650 to £2,400 and fibreglass at £1,800 to £2,700. Those ranges are theirs, not ours.
How much does a new flat roof cost in the UK?
MyJobQuote's flat roof replacement cost guide puts the average new flat roof at £2,400, with a 2026 range of £1,500 to £6,000, and prices the covering by the square metre installed: felt £80 to £120, rubber £110 to £160, fibreglass £120 to £180.
Which? prices a garage instead. It puts a felt flat roof on a 6m by 3m garage, without new boards, at £1,400 to £3,500, and the same garage with new boards in other materials, which it gives as PVC or rubber EPDM, at £1,950 to £4,000. Those November 2025 figures include labour and materials and exclude VAT.
Which?'s garage measures 6m by 3m, which works out at 18 square metres. MyJobQuote's single garage is 15. Read the two side by side, not as one range.
Every range here belongs to the publisher named beside it, not to us. We give a free estimate. Some roofs we price over the phone, some we come and look at.
What does a flat roof cost on an extension, a dormer or a porch?
An extension. MyJobQuote's flat roof replacement cost guide gives £800 to £3,500.
A dormer. MyJobQuote's flat roof replacement cost guide gives £900 to £1,800.
A porch. MyJobQuote's flat roof replacement cost guide gives £400 to £1,200.
A double garage of 20 to 25 square metres. MyJobQuote's flat roof replacement cost guide gives £1,600 to £3,000 in felt, £2,200 to £4,000 in rubber and £2,400 to £4,500 in fibreglass.
What moves the price of a flat roof
What is underneath. MyJobQuote's rubber roofing cost guide says a damaged or rotten deck can add significantly to the price, in some cases close to doubling the total project price, and nobody knows the state of a deck until the covering is off.
Access. MyJobQuote's flat roof replacement cost guide puts scaffolding at £800 to £1,200 where it is needed, and its rubber roofing cost guide puts a small tower on a single-storey job at £600 to £1,200.
The build-up. MyJobQuote's fibreglass roofing cost guide prices an insulated fibreglass roof at £210 to £270 per square metre, against a covering only at £35 to £45.
VAT. Which? excludes it from its prices. MyJobQuote says VAT is something to clarify with the contractor.
When a repair is the job, not a new roof
A flat roof that leaks in one place has not necessarily failed. If the deck is firm and one seam or one edge has let go, the repair is the job.
MyJobQuote's flat roof replacement cost guide prices repairs on the same page: a felt patch or reseal £100 to £300, a rubber puncture or edge repair £150 to £400, a fibreglass crack repair £200 to £500.
A deck that gives underfoot, standing water, or blistering across the whole surface is a different answer, and we will tell you which of the two you have got.
Those repair figures are MyJobQuote's, not ours. Ring 07477 536 273 for a free estimate.
What to ask before you accept a flat roof price
Strip or overlay. Ask whether the old covering is coming off or going under the new one.
A soft deck. Ask what happens if the deck turns out to be soft once the covering is up.
What sits inside the figure. Ask whether insulation, scaffolding, waste removal and VAT are in it: MyJobQuote lists insulation upgrades among the things not typically included.
Fall and drainage. Ask what fall the roof will have and which way it drains.
Where these figures come from
Every price on this page is quoted from a published cost guide, named in the text beside it. Nothing here is averaged or estimated.
MyJobQuote, Flat Roof Replacement Cost: How Much Is a New Flat Roof?, https://www.myjobquote.co.uk/costs/flat-roof-construction-cost, read 2026-08-31
MyJobQuote, How Much Does a Fibreglass Roof Cost? (2026 UK Prices), https://www.myjobquote.co.uk/costs/fibreglass-roofing, read 2026-08-31
MyJobQuote, Rubber Roofing Cost: How Much Is Rubber Roofing? (2026), https://www.myjobquote.co.uk/costs/rubber-roofing, read 2026-08-31
Which?, How much do roof repairs cost?, https://www.which.co.uk/reviews/finding-a-tradesperson/article/how-much-do-roofers-cost-aHH2S2r0xnGA, read 2026-08-31
Common questions
- Is GRP the same as fibreglass?
- Yes. GRP stands for glass reinforced plastic, which is fibreglass. EPDM and rubber are the same thing as each other too. A quote listing all four as different materials is listing two materials twice.
- How long does a new flat roof take?
- MyJobQuote's flat roof replacement cost guide says most flat roof jobs take 2 to 3 days, a single garage 1 day and a double garage 2 to 3 days.
The work this is about
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