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Flat roof cost calculator for UK roofers and builders.
Measure it, pick the material, then price it from your own rates.
Quick answer
Measure the roof, pick the material and see what published UK per-m² averages suggest. Checkatrade's guide puts a standard flat roof at around £75 per m² (£50 to £110), EPDM rubber at around £90, GRP fibreglass at around £107.50 and torch-on felt at around £65. Its cost table was last updated in December 2024, so treat the figures as a floor to check against, not today's price. Then put in your own cost per m², preliminaries, contingency, markup and VAT.
Source note: Per-m² figures come from Checkatrade's "Flat roof replacement costs in 2026". The page is marked updated February 2026, but its cost table is marked "Last updated: December 2024". VAT points come from HMRC VAT Notice 708 (last updated 26 August 2026) and GOV.UK's VAT rates page. Figures checked 26 October 2026. Checkatrade calls them ballpark averages and heads the columns "cost per m² (+VAT)".
Flat roof cost calculator
Use the roof area and the material to rough out the job before doing a full quote.
Published average for this area
£1,260
Published range
£1,120 to £1,400
Checkatrade per-m² averages (table dated December 2024), times your area. Roof covering only: strip-out, scaffolding, skips, insulation and gutters are extra.
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Published per-m² figures by material
| Material | Low to high per m² | Average per m² |
|---|---|---|
| Felt (bitumen) | £50 to £80 | £65 |
| EPDM rubber | £80 to £100 | £90 |
| GRP fibreglass | £95 to £120 | £107.50 |
| Asphalt | £50 to £70 | £60 |
| Green roof | £75 to £110 | £100 |
| Liquid coating | £20 to £28 | £24 |
Checkatrade gives a standard flat roof replacement overall at £2,800 to £7,500, and converting a flat roof to pitched at £3,000 to £4,500.
Extras that sit outside the per-m² price
Checkatrade lists these as extra costs to budget for, with figures from its own calculator: roof inspection about £260, removing the existing roof about £2,000, scaffolding about £900 a week, a skip about £300, insulation about £960 and gutter installation about £775. It also mentions fascias and soffits, and working round skylights. Price each one from your own rates as its own line. If the deck or insulation needs upgrading to meet Building Regulations, say so on the quote. To lay it out, use the flat roof quote template.
Which material, and how long it lasts
Checkatrade's lifespans: torch-on felt 15 to 20 years, EPDM 30 to 50 years when professionally installed, GRP up to 30 years, asphalt 20 to 30 years. Put the material, the system and any guarantee on the quote, so the client can compare like with like.
VAT
HMRC VAT Notice 708 says work to an existing building is normally standard-rated (20%). For wording, see VAT quote wording.
FAQ
How much does a flat roof cost per m² in the UK?
Checkatrade's guide gives around £75 per m² for a standard flat roof, with a range of £50 to £110. Its table was last updated in December 2024.
How much is an EPDM rubber roof per m²?
Checkatrade gives £80 to £100 per m², around £90 on average.
How much is a GRP fibreglass roof per m²?
Checkatrade gives £95 to £120 per m², around £107.50 on average.
Does the per-m² price include stripping the old roof?
No. Checkatrade lists removing the existing roof, scaffolding, skips, insulation and gutters as extra costs. Price them as separate lines.
Can this calculator replace a survey?
No. The deck, falls, outlets, insulation and access all need checking on the roof before you send a price.
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