Flat roof costs
What is the cheapest flat roof covering?
The short answer
Torch-on felt is generally the lowest-cost flat roof covering to buy and lay, ahead of EPDM rubber and GRP fibreglass. Checkatrade's repair guide, for instance, puts bitumen flat roofing at £100 to £140 a square metre against £120 to £170 for EPDM and £130 to £180 for GRP. Felt also tends to have the shortest life, so the lowest price up front is not always the best value over the years.
How the main flat roof coverings compare on price and lifespan, and what shifts the cost of your roof more than the material does.
The three coverings most homes choose from
Nearly every flat roof on a house, extension or garage wears one of three coverings. Torch-on felt is bitumen roofing felt, laid in layers and heated so they fuse together. EPDM is a single sheet of synthetic rubber, glued down to the deck. GRP is glass-reinforced plastic, a fibreglass layer laid wet in place and finished with a topcoat. Each suits different roofs, and each has its own price and its own way of going wrong.
Felt is the oldest and most familiar. It copes with awkward shapes and is easy to repair. EPDM arrives in large sheets, so a simple roof can be covered with few or no joins. GRP sets hard and without joints, which makes it popular for balconies and walk-on areas.
Our guide to EPDM, GRP and felt compares them in more depth. Here the only question is price, and price depends on the roof as well as the covering.
What the published figures show
Checkatrade's roof repair guide, with a pricing table dated June 2026, gives typical repair costs per square metre of £100 to £140 for bitumen flat roofing, £120 to £170 for EPDM and £130 to £180 for GRP. The guide states that its costs exclude VAT, which must be added. The ranges overlap, so the order is a tendency and not a rule, but felt sits lowest and GRP highest. Remember too that these figures are for repair work, so they show the relationship between the coverings and not the price of a complete roof.
For a complete new flat roof, Checkatrade's replacement guide (October 2026) gives a typical UK range of £2,800 to £7,500, plus VAT. That range spans every covering, and it is wide because a small garage roof and a large extension roof are very different jobs.
Those are national typical figures and not our prices. What your own roof costs is fixed by the written quote after our survey, a single figure for the whole job, and it can sit above or below these ranges depending on access, condition and size.
Why the lowest price is not always the lowest cost
A covering that costs less to lay but needs replacing sooner is not saving you anything. Typical lifespans differ. Less gives torch-on felt a life of 10 to 20 years, and says careful laying can take felt to 20 years while sloppy work can end it inside 10. For EPDM, Less says 30 to 50 years and GreenSpec says 20 to 30. For GRP, Less says 25 to 40 years.
These are typical ranges, not promises, and they depend on how the roof is laid and looked after. A well-laid felt roof may outlive a badly laid rubber one.
If a roof is only a few years from replacement anyway, such as a garage you may demolish, the lowest-cost covering can be the right one. On a roof you plan to keep for decades, such as a kitchen extension, the extra spend on a longer-lived covering is often worth it. Our answer on how long a flat roof lasts goes into the detail.
What moves the price more than the material
Size is the obvious factor, but it is not the only one. Access matters: a roof that needs scaffold costs more to reach than one a ladder serves. Checkatrade's scaffolding guide quotes about £875 per month for a typical two-storey semi, and if a quote leaves scaffold out, that has to be added on top.
The deck underneath counts. Rotten boards must be replaced, and a roof laid without proper falls will hold water. BS 6229:2025 sets a minimum finished fall of 1:80, and roofers tend to design steeper, around 1:40, so the finished roof still drains. Insulation, edge trims, rooflights and upstands all add to the work.
Treat a figure well under all the others with caution. It may leave out the deck repairs, the falls or the edge details, which are the parts that decide how long the roof lasts. Find out whether each price includes VAT and scaffold, so that you are comparing like with like.
Choosing on the survey, not the brochure
The right covering depends on the roof's shape, its condition and what you want from it. A small, simple roof that will be replaced again in 15 years may suit felt. A larger extension roof you want to forget about for decades may suit EPDM or GRP. A roof you will walk on needs a covering built for foot traffic, and that changes the sums again.
The survey covers the roof with photographs of what is found, and the verdict is plain: repair, overlay or full replacement. Where a repair will hold, you are not sold a new roof. Our flat roof cost guide sets out the typical figures, and our flat roofing page explains the work.
The written price that follows is a single total. Where a lower-cost covering is the right one for the roof, that is the one we recommend.
Related questions
Flat roof covering questions
Is felt always lower in price than EPDM?
Not always. On the published per-metre repair figures felt sits lowest, but the ranges overlap, and on a large simple roof the speed of laying a single EPDM sheet can narrow the gap. The survey and the written quote show the actual difference for your roof.
Is it possible to lay the new covering over the existing flat roof to save money?
Sometimes, if the existing deck and covering are dry and sound, but it does not suit every roof. Trapped moisture or poor falls would stay with the old layers. Our overlay answer explains when it works, so ask about it at the survey.