Felt or EPDM for a garage roof?

On installed cost, felt comes in below EPDM. In MyBuilder's August 2026 flat roof pricing, bitumen felt runs £70 to £100 per m² against £90 to £130 per m² for EPDM. The same guide lists GRP at £95 to £150 per m², which gives a sense of where the two sit among the flat-roof options.

On a single garage the difference is a modest sum, and it is worth setting against how many years each gives you. For whole garages, MyBuilder's garage pricing is £700 to £1,000 for a single flat roof and £900 to £1,400 for a double, and the covering is only part of a total like that, since the deck, edge trims and clearing the old roof come into it. Your quote shows VAT and arrives after the survey, covering scaffold, deck work and covering.

Less describes built-up felt as lasting 10 to 20 years, and notes that a careful felt job can reach 20 while a careless one could fail within 10. EPDM is quoted at 20 to 30 years by GreenSpec, and in excess of 25 years by the Building Centre. The two ranges touch at about 20 years, which is the honest picture: a very good felt roof can match a modest EPDM one, and a badly laid EPDM roof can fail early.

Where the sources diverge, we take the cautious end. Plan on felt for around a decade or two and EPDM for two to three decades, and read both as typical figures, never promises. Our wider answer on how long a garage roof lasts sets out the sources in full.

Built-up felt goes down as layers of bitumen-based sheet, stuck to the deck with heat or adhesive. Because it goes down in overlapping strips, a felt roof has seams at every lap, and the quality of those seams is most of the job. It is also the covering that most shows the hand of whoever laid it.

EPDM is rubber membrane that arrives in big sheets, often cut to cover a whole small roof in one piece. A single garage can sometimes be done with no seam across the field of the roof at all, so the only joins are at the corners, edges and upstands. Those are formed with adhesive and tape or flashing pieces, and they are where any leak is most likely to start. A clean deck and well-formed corners matter more with EPDM than the membrane itself.

Both coverings can be repaired. A split in felt is usually cut out and patched; an old, brittle felt roof with many splits is nearer the end of its life than a patch suggests. EPDM is repaired with a cleaned, primed patch of matching rubber. Rubber copes with movement better than aged felt, but it can be punctured by a ladder foot or a falling branch.

Neither covering takes foot traffic well, and whoever goes up for a gutter clear should lay a board across the surface to spread their weight and keep boots off the laps. Sharp edges on dropped tools and the corners of ladder feet are the usual causes of punctures, and a puncture left unfound for a winter can wet the deck underneath for months. If a garage sheet roof is the one you are replacing, that is a different job from either of these; see our answer on a cracked asbestos sheet before touching it.

Neither membrane rescues a poor deck. Both need a dry, sound, firmly fixed surface with a fall to an outlet, and on a garage that surface is often old boarding or a concrete slab that has moved over the years. If the boards are soft, they are replaced before anything goes on. If the roof ponds, the falls are corrected with a tapered layer or by re-laying the deck. BS 6229, as quoted by IKO and Rockwool, designs for a 1:40 fall, which leaves a finished roof falling at 1:80.

Garages also have a tendency to be cold, unheated and unventilated, so condensation under a sealed roof can rot the deck from below. Before recommending either covering we study the ceiling and boards from inside the garage, checking for stains and tapping for hollow patches. That check is one of the first things we do at the survey, and it often matters more to the roof's life than the choice between felt and EPDM.

Pick felt if the budget is tight, you expect to convert or rebuild the garage within ten to fifteen years, or the roof is small and simple. Pick EPDM if you want to fit once and not return for decades, or the roof is awkward in shape. The deck underneath, the falls and the gutter matter as much as the covering you choose, and a good survey looks at all three.

Our guide to garage roof materials brings GRP and sheet into the comparison, and garage roof insurance covers what your policy may say if the roof fails. For the whole job, see garage roof replacement in Stroud. Your own roof is photographed at the survey, we take the waste away, and the finished work comes with a 10-year workmanship guarantee in writing.