How much does a flat roof replacement cost in the UK?
A flat roof replacement costs £90 on average in the UK. Most jobs fall between £60 and £130 per m². Roof covering: Felt £60 to £80, EPDM rubber £70 to £110, GRP fibreglass £90 to £130. Prices reviewed September 2026.
A flat roof replacement is priced per square metre, and the material is the biggest factor. Felt is the cheapest, EPDM rubber sits in the middle, and GRP fibreglass is the most expensive. Access, the state of the timber deck underneath, and roof size also move the price.
Flat roof replacement cost calculator
Use the calculator to price your flat roof replacement in 2026. Adjust the options and area for a UK cost range. Nothing is sent anywhere.
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Flat roof replacement cost breakdown
Typical flat roof replacement costs, by the unit:
| What | Typical UK cost |
|---|---|
| Per m², supplied and fitted | £60 to £130 per m² |
| + Two-storey roof needing scaffolding | add £15 to £35 per m² |
| + New timber deck needed | add £20 to £45 per m² |
| 10 m² | £600 to £1,300 |
| 20 m² (typical) | £1,200 to £2,600 |
| 40 m² | £2,400 to £5,200 |
Flat roof replacement cost by roof covering
A flat roof is priced by the covering you choose and the area it covers. Felt is the cheapest to lay and the shortest-lived, EPDM rubber is one sheet with no joints on most house roofs, and GRP fibreglass is the rigid, seamless finish at the top of the range. A new timber deck and scaffolding are extras on every covering.
| Roof covering | Cost per m² installed on a sound deck | Best for |
|---|---|---|
| Felt (torch-on) | £60 to £80 | Garages, sheds and porches on a tight budget |
| EPDM rubber | £70 to £110 | Most extensions and garage roofs; one sheet, no seams to fail |
| GRP fibreglass | £90 to £130 | Roofs that are walked on, have upstands and outlets, or need a hard finish |
Supplied and fitted, per m² installed on a sound deck. UK guide prices reviewed September 2026, not quotes.
What's included in the price?
Typical flat roof replacement prices include:
- Stripping and disposing of the old covering
- The new membrane and a new timber deck where needed
- New edge trims, drips and flashings
- Labour and standard ground-level access
What changes the price?
The things that move flat roof replacement prices most:
The material: felt, EPDM rubber or GRP fibreglass
Whether the deck or firrings need replacing
Roof size and how the roof is reached
Scaffolding or an access tower on a two-storey roof
How the price is built up
Most of the price is the per square metre rate for tearing off the old covering and fitting the new one, which runs from £60 to £130 and sits around £90 on a typical job. On the standard 20 square metre roof that puts the core work near £1,800, with felt at the bottom of the band and GRP fibreglass or a thicker EPDM rubber system towards the top. Two things push a job higher. A two-storey roof needs scaffolding or an access tower, adding £15 to £35 per square metre, and a rotten deck or firrings that must be replaced adds £20 to £45 per square metre for new timber before the covering goes down. Labour is usually the larger share on a flat roof, roughly 55 to 65 percent of the total, with the covering, timber and fixings making up the rest. The split tilts further towards labour once scaffolding or a full deck strip is involved.
Ways to keep the cost down
- Choosing felt over GRP fibreglass or a premium EPDM rubber system keeps the covering near the £60 floor rather than the £130 top, so on a 20 square metre roof that is roughly £1,200 against £2,600.
- Only replace the deck and firrings if they are actually rotten. Sound timber avoids the £20 to £45 per square metre new deck charge, so ask the roofer to lift and check before you agree to a full strip.
- Book work outside the busy summer and autumn stretch. Winter and early spring are quieter for roofers, so quotes tend to soften when they are chasing work.
- A single-storey roof avoids the £15 to £35 per square metre scaffolding charge that a two-storey job carries, so make sure your quote is not padded with access costs you do not need.
Does where you live change the cost?
In London, a flat roof replacement typically costs around £110 per m², about 20% above the UK average of £90. In the North, Scotland and Wales the guide figure is nearer £85.
| Region | From | Typical | Up to |
|---|---|---|---|
| Midlands / East (UK average) | £60 | £90 | £130 |
| London | £70 | £110 | £160 |
| South East / South West | £65 | £95 | £140 |
| North / Scotland / Wales | £60 | £85 | £130 |
Guide prices per m², scaled with the same regional multipliers as the calculator. Not quotes.
Flat roof replacement cost in major UK cities
| City | From | Typical | Up to |
|---|---|---|---|
| Belfast | £55 | £85 | £120 |
| Birmingham | £60 | £90 | £130 |
| Bristol | £65 | £95 | £140 |
| Cardiff | £60 | £85 | £130 |
| Edinburgh | £60 | £85 | £130 |
| Glasgow | £60 | £85 | £130 |
| Leeds | £60 | £85 | £130 |
| Liverpool | £60 | £85 | £130 |
| London | £70 | £110 | £160 |
| Manchester | £60 | £85 | £130 |
| Newcastle | £60 | £85 | £130 |
| Sheffield | £60 | £85 | £130 |
City guide estimates, scaled by local labour costs. Indicative averages for flat roof replacement, not quotes.
Nearly all of the regional gap is labour.
Compare this with a real quote
The figures above are guide prices. Two or three quotes for your flat roof replacement tell you what it costs where you live.
Common questions
How much does it cost to replace a flat roof on a garage?
A single garage of around 15m² typically costs £1,200 to £1,800 in felt, or £1,650 to £2,700 for EPDM rubber or GRP fibreglass, supplied and fitted.
How much is an EPDM rubber flat roof per square metre?
EPDM rubber usually costs £70 to £110 per m² fitted, so a 20m² roof works out at roughly £1,400 to £2,200.
How often do flat roofs need replacing?
Traditional felt lasts 15 to 20 years, GRP fibreglass 25 to 30, and EPDM rubber 30 or more. If your felt roof is on its second decade and showing bubbles or cracking, budget for replacement rather than another patch: at £60 to £130 per m² a garage roof is often a £1,200 to £2,600 job.
Is a leaking flat roof covered by home insurance?
Storm damage usually is: a roof that was sound until a specific event. Gradual deterioration is not, and insurers treat a worn-out felt roof as a maintenance issue. That distinction is why it pays to photograph your roof condition periodically and fix small defects before winter.
Is it better to repair or replace a flat roof?
Replace it once the deck is soft or the covering has failed across most of the roof, because patch repairs on a worn surface rarely last. A full replacement at £60 to £130 per square metre resets the roof for years, whereas a repair only buys time on a covering that is near the end of its life. If the damage is one small area and the timber underneath is sound, a repair is the cheaper and sensible choice.
How easy is it to replace a flat roof?
It is skilled work rather than a straightforward DIY job, which is why the fitted rate runs £60 to £130 per square metre. EPDM rubber is the simplest to lay because it goes down in a single sheet with adhesive, whereas felt needs a torch and heat, and GRP fibreglass is laid wet and left to cure. A two-storey roof also needs scaffolding, adding £15 to £35 per square metre, so most homeowners use a roofer.
What time of year is the cheapest to replace a flat roof?
Winter and early spring tend to be cheapest, because roofers are quieter once the summer and autumn rush eases and are more willing to price keenly for work. Dry, mild spells still matter, as felt and GRP fibreglass need reasonable conditions to bond and cure, so a settled winter week is better than a wet one. The saving comes from demand, not from any change in the £60 to £130 per square metre rate itself.
Can I replace a flat roof myself?
On a small shed or garage you can, and since labour is roughly 55 to 65 percent of the total at £60 to £130 per m2, doing it yourself saves a real amount. The catch is the falls and the joints. Water sits on a flat roof, so a slight dip or a poor seam leaks. Felt and EPDM take skill to lay flat and bond, and scaffolding or a full deck strip pushes the job past most DIYers.
Is it worth replacing a flat roof rather than patching it?
If the deck is sound and the leak is one spot, a repair is cheaper. Once the covering is at the end of its life or the timber is wet, a full replacement at £60 to £130 per m2 is the honest fix, because patches on old felt keep failing. A new flat roof does not add much resale value on its own, but a dry, sound roof avoids far bigger damage below.
Do I need building regulations approval to replace a flat roof?
For a full replacement, yes, and flat roofs get an unusually clear rule. Regulation 2 of the Building Regulations 2010 excludes a new layer provided solely as a means of repair to a flat roof from counting as renovating a thermal element, so patching a leak is not notifiable. Replacing the covering is, because regulation 23 then requires the element to be upgraded where the work is a major renovation or covers more than 50 per cent of its surface area. Most roofing sites quote 25 per cent, which is the regulation 35 definition of a major renovation, work to more than a quarter of the whole building envelope, and not a threshold for the roof on its own. Either way a full replacement clears the threshold, so use an installer who can self-certify under a competent person scheme, or notify building control yourself, and keep the certificate.
How much does a fibreglass (GRP) flat roof cost per square metre?
A GRP fibreglass flat roof costs £90 to £130 per square metre supplied and fitted on a sound deck, so a 20 square metre garage roof is £1,800 to £2,600. A new timber deck adds £20 to £45 per square metre and scaffolding for a two-storey roof £15 to £35 per square metre. GRP sits at the top of the flat roof range because it is laid wet as a resin and matting system and cured into one rigid, seamless skin, which takes more skill and more time than rolling out a sheet, and it is the covering to choose where the roof is walked on or has upstands and outlets to seal.
Official guidance and sources
The rules and schemes referenced on this page come from these official UK sources. The price figures are Costwise's own; see how we price.
- Building Regulations 2010, regulation 23 legislation.gov.uk · Requires a thermal element to be upgraded where the work is a major renovation or covers more than 50 per cent of its surface area.
- Building Regulations 2010, regulation 35 (interpretation of Part 6) legislation.gov.uk · Defines a major renovation as renovating more than 25 per cent of the whole building envelope, meaning the walls, floor, roof, windows, doors, roof windows and rooflights together.
- Building Regulations 2010, regulation 2 legislation.gov.uk · Defines renovating a thermal element, and excludes a new layer provided solely as a repair to a flat roof.
- Roofs: insulation and thermal elements Planning Portal · The official summary. Note it says significant changes without naming a percentage.
Cite this data
These figures are free to use in articles, reports and research under a CC BY 4.0 licence. All we ask is a credit to Costwise, and online a link. Where your style allows, please make "Costwise" the linked word so readers can check the figure for their own region.
Costwise (2026): A flat roof replacement typically costs £90 in the UK, ranging from £60 to £130 per m². Reviewed September 2026. costwiseuk.co.ukSource: Costwise (costwiseuk.co.uk)Costwise (2026). Flat roof replacement cost. Costwise UK cost data, version 2026-09-28. https://costwiseuk.co.uk/flat-roof-replacement-cost/2026-09-28 (156 jobs)Dataset DOI: 10.5281/zenodo.21159943 · also on Kaggle, Hugging Face and Figshare. Method: how we price. Downloadable CSV.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing.