Flat roof cost
How much does a new flat roof cost?
Published prices for a new flat roof cover a wide range, because roofs differ. Below: three sources, what moves the price, and what a quote should name.
The short answer
The published ranges from Which? and MyJobQuote run from £1,400 to £6,000, depending on the covering and the roof. Which? put felt for a typical single garage (6m x 3m) at £1,400 to £3,500 in November 2025, excluding VAT. MyJobQuote's 2026 average for a flat roof replacement is between £1,500 and £6,000. Your own price comes as one written total after a survey.
4 min read · Part of Flat roofing
Three published price ranges
The year matters, because a published price ages. Each source prices a different thing, so they are shown with what they measured. Treat them as context: they are not a quote for your roof, and they are not our prices.
| Source | What it priced | Range |
|---|---|---|
| Which?, November 2025 | Felt on a typical single garage (6m x 3m) | £1,400 to £3,500, excluding VAT |
| Which?, November 2025 | Rubber (EPDM) or PVC, with new boards | £1,950 to £4,000, excluding VAT |
| MyJobQuote, 2026 | Average flat roof replacement | £1,500 to £6,000 |
Which? based these prices on a survey of 11 Which? Trusted Traders, with prices that include labour and materials. In London or the South East, Which? says, prices are likely to be at the upper end of the scale, and Kent and East Sussex are in the South East.
The two Which? rows share a sample and a date, so they can be compared with each other. The MyJobQuote range comes from a different source, so it is best read as a rough outer frame, not a match.
Reading the figures with care
A range is a spread of different roofs, not a promise about one. The felt figure is for a single garage, which is a plain rectangle; an extension with upstands, a rooflight and an awkward corner is a different job. Rubber has a figure of its own: MyJobQuote's rests on around £60 per square metre, and it says the average rubber roof costs £1,050 fully installed. That is MyJobQuote's average for its typical roof, not a rate to scale up by the area of yours.
Three habits keep these numbers useful:
- check whether VAT is in any figure you are shown, because Which? leaves it out and other pages do not say
- never multiply a price per square metre by your roof area to get a total
- treat two sources that differ as a spread, not a mistake
A figure near the bottom of a range suits a plain roof in good order, and one near the top suits a roof with more to do. A cheaper figure that leaves out the deck or the falls can end up dearer once the covering is off, so ask what the total includes. Insulation is part of the work whenever a roof is renovated, so a price that ignores it is incomplete.
What moves the price of a flat roof
Each flat roof is priced as the survey finds it. These things move the figure:
- how big the roof is, what shape it is, and how many edges and corners it has
- the covering you choose: EPDM, GRP or felt
- whether the deck and the falls need rebuilding, which only a survey reveals
- the insulation, because a renovated roof is brought towards the improved figure in Table 4.3 of Approved Document L, 0.16 W/m²K against a 0.35 threshold, where that is feasible
- upstands, trims, outlets and any rooflights
- access, with scaffold included in the written quote
A cold deck that has to become a warm deck is a bigger job than one left as it is, and our warm deck or cold deck answer compares the two. A roof that needs only patching is priced on the patch, and the survey says which kind you have.
None of this is a menu. It is the list of questions the survey answers before a total price is written, in the order we ask them.
What a written quote should say
Whoever you ask, a quote for a flat roof should be a document, not a number said aloud. It should state:
- one total price, in writing, given after the roof has been looked at
- whether VAT and scaffold are included in that total
- the covering and the build-up, so you can see what goes on the roof
- what happens to the deck and the falls if they turn out to need work
- that the site is left clean
Ours is given after a survey, because the deck and the ceiling beneath tell us more than a plan or a photograph does. If a quote differs sharply from the figures above, the reasons should be on the page, and you are entitled to ask for them before you sign.
Be wary of a figure given without a visit, and of any quote that cannot say what the roof is made of. A written total that names the covering and the build-up is easy to set beside a second one.
Our flat roofing page explains how the survey turns into a verdict and a price.
More questions
Why do published flat roof prices vary so widely?
Roofs differ in size, shape, covering, deck condition and insulation, and each source measured a different sample of roofs. Which? surveyed a group of tradespeople on a typical single garage, while MyJobQuote gives an average for the whole country. A wide range is the plain picture, which is why a fixed price waits for a survey.
Can the price rise once the old roof is off?
The survey lifts samples to catch hidden faults before a price is set. If something cannot be seen until the covering is off, the written quote says what has been assumed and what would change it, so a change comes as no surprise. You are told before any further work goes ahead.
Tell us what's wrong with the roof.
You'll get one written total price.