Question answered
What is the cheapest flat roof covering, and is it worth it?
The short answer
Torch-on felt is the lowest-priced of the three common coverings, at £70 to £100 per m² against £90 to £130 for EPDM and £95 to £150 for GRP (MyBuilder, updated 21 August 2026). Felt is also expected to last the fewest years, so the lowest price on the day is not always the lowest cost across the life of the roof.
Of the common flat roof coverings, felt has the smallest typical price per square metre. Whether that makes it the sensible choice depends on how long each covering lasts and what sits underneath it.
Three coverings and what each costs to lay
The MyBuilder flat roof guide, updated on 21 August 2026, sets out typical UK ranges per square metre. Felt, which in practice means torch-on or bitumen membrane in layers, comes at £70 to £100. EPDM, one large sheet of synthetic rubber, comes at £90 to £130. GRP, which is glass matting set in resin and sold as fibreglass, comes at £95 to £150.
The ranges overlap. A plainly shaped roof laid in EPDM can cost less than a fussy one in felt, because the number of details drives the price as much as the material does. The overlap is the first reason a per-metre comparison on its own can mislead.
Treat them as a national picture drawn from one published guide, which cannot predict what any roofer will charge on the Sussex coast. Only a survey of your roof tells you where in a range you land, and the written quote then carries a single total.
Lifespan changes the sum
A flat roof of any kind typically lasts between 15 and 30 years, according to MyBuilder. The coverings differ inside that band. Less, a cost guide updated in March 2026, puts torch-on felt at 10 to 20 years and adds that a poor job might fail in under 10. GreenSpec lists EPDM at 20 to 30 years, and Less at 30 to 50, so 20 to 30 years or more is a fair reading. Less puts GRP at 25 to 40 years.
Now set cost against life. A covering that costs a quarter less to lay but needs replacing a decade earlier has not saved anything, because the scaffold, the stripping and the disposal come round again. The lowest figure today can become the highest bill over thirty years.
Every one of these lifespans is a typical range. Workmanship, exposure to sea weather and how often the roof is looked at all push a real roof either way.
Where a low price quietly costs more
The membrane is just the top layer. A saving that comes from skipping repairs to rotten boards, leaving old wet insulation in place or laying over a dip that holds water will show up as a leak, usually within the first few winters. A new covering does nothing to make a damaged deck sound, and it can bury the damage for whoever inspects the roof later.
The build-up beneath matters too. Whether insulation sits above the deck or below it alters how the roof behaves in cold weather, and we compare the two in our page on warm and cold flat roofs. Details such as edge trims, upstands and outlets are also where a low-priced job tends to economise, and these are the places leaks start.
Weigh up what a decent specification includes before you set one figure against another. Two quotes for the same roof can be far apart simply because one of them leaves out half the work.
When a lower-priced covering is the right call
Sometimes it is. A small roof over a garage or a store, where the building itself has a limited future, does not always justify the longest-lived covering. A roof that will be taken off in a few years for an extension is another case. In those situations a well-laid felt roof can be a sound, honest answer.
Equally, a long-lived covering is not automatically right. If the deck is sound and only one corner has failed, a repair that closes that corner is the right job, and a full new roof would be money spent for nothing.
Our rule is to match the covering to how long the building will need it, how complicated the roof is and what the survey finds. We say which route we would take and why, and show the photographs that led there. The typical EPDM price has a page of its own if that is the option you are leaning towards.
Questions to put to any roofer
Our flat roofing page covers the full range of work. Whichever route you take, ask what is being laid and how long that covering is generally expected to last, and be wary of a promise that sounds longer than the published ranges. Ask whether the deck will be inspected once the old layer is off, and what the arrangement is if boards need replacing.
Check whether the figure includes VAT and scaffolding, since either can make two prices look further apart than they are. Ask for any guarantee in writing, with what it covers and whether insurance stands behind it.
Keep the survey photographs, the paperwork and the invoice. A tidy file helps if the roof ever needs repair work, and it matters if an insurer asks about the roof, which we cover in why insurers ask about flat roofs.
Our quotes come after the survey, in writing, and we aim for a figure that reads as fair against the work described.
Choosing a covering: two more questions
Does a lower price per metre mean a worse roof?
No, price and quality are separate. A low figure for a simple roof can be entirely reasonable. What deserves a second look is a price that sits well below every published range for the same covering, because something may have been left out: deck repairs, edge trims, drainage or the removal of the old layers.
Which covering suits a small garage roof?
MyBuilder's garage roof guide gives felt at about £75 per m², GRP at about £125 and EPDM at £70 to £100. On a small, plain roof, EPDM can come out level with felt, so the choice may rest on life expectancy and how the roof is reached for repairs rather than on price.
Tell us about your roof
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- Photographs of what we find
- A written quote with one total price
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