The short answer
Felt is cheaper to buy and is laid in layers with seams that need good workmanship. EPDM arrives as one rubber sheet with hardly a joint and a longer quoted life, but usually costs more. MyBuilder's garage guide, updated August 2026, gives felt at about £75 per m² and EPDM at £70 to £100 per m². For most garages the roof shape and edge detail matter more than the headline price.
How the two materials are built
Torch-on felt is a bitumen sheet reinforced with polyester. A roofer unrolls it, heats the underside with a gas flame and welds it to the layer below. A good system has two or three layers: a base, then a cap sheet with a mineral or smooth surface. Joints are lapped and sealed. Because everything depends on those welds, the skill of the person with the torch is the biggest variable.
The full name is ethylene propylene diene monomer, though on site it is simply rubber sheet sold in wide rolls. On a garage the sheet is usually cut to one piece, laid over a deck on adhesive and tucked up at the edges. It has no flame and few seams, and that is part of the appeal. Corners are made with preformed pieces, and trims finish the edge. Tape or adhesive joins separate pieces where the roof is large.
Both sit on a deck, normally plywood or OSB boards, with an insulation layer where the garage is heated or converted. No covering outperforms the deck beneath it.
Lifespan and warranty claims
Published ranges disagree, which is useful to know. For EPDM, GreenSpec states an expected service life of 20 to 30 years, while Less gives 30 to 50 years and says manufacturer warranties of 20 to 25 years are standard. CORC goes further and says EPDM that is looked after can pass 50 years. For torch-on felt, Less says 10 to 20 years, adding that a good job can last 20 while a poor one can fail before reaching 10. CORC puts well-maintained torch-on at 30 years or more.
A sensible reading is that EPDM often outlasts felt when both are installed well. A warranty is not a lifespan, though, and a manufacturer's document does not cover poor workmanship by whoever fitted it. The workmanship guarantee that matters is the one from the person doing the work. Ours runs for ten years on paper and is not an insurance product.
Cost and what drives it
MyBuilder's garage roof replacement guide, updated August 2026, gives typical figures of £700 to £1,000 for a single flat garage and £900 to £1,400 for a double. By material it quotes felt at about £75 per m² and EPDM at £70 to £100 per m², with GRP at about £125 per m². Checkatrade's roof replacement page, updated October 2026, puts re-felting a garage at around £1,000 to £2,000, with an average of £1,500.
The overlap tells you something. On a small roof the material cost is only part of the bill, and labour, deck repairs, edge trims, flashing, waste and access make up the rest. A roof with a rotten deck costs more whichever covering goes on top. EPDM can look dearer per square metre on a tiny roof, because the sheet comes in set widths and the offcut is wasted.
Written quotes come after a survey as one total price. Check whether each quote includes VAT, the removal of the old covering and any scaffolding, because a lower figure that leaves those out is not a saving.
Which suits which garage?
Felt makes sense where the roof is simple and the budget is tight, or where the owner wants a modest roof for a modest outbuilding. It is easier to repair locally, a patch of new felt can be welded to old, and every roofer knows the system. It makes less sense on a roof with many penetrations, curved sections or heavy foot traffic.
EPDM suits garages with awkward shapes, rooflights, upstands and a wish for a lower-maintenance roof. Its large sheets mean fewer seams to fail. It is weaker against sharp objects dragged across it, and a repair needs the right adhesive and patch.
Our guide to the tiled and sheet pitched garage roofs covers the alternative when the roof is not flat at all, and our page on how long a garage roof lasts sets lifespans side by side for every covering.
Edges, falls and the faults that cause leaks
Either covering will leak if the roof ponds. IKO, citing BS 6229:2018, gives the recommended minimum fall for a flat roof as 1:80 and says to design for 1:40 so tolerances and deflection leave the finished fall above the minimum. Old garage decks are often dead level or dished, and a new covering over them holds water. Furring strips or tapered boards put the fall back.
Edges are the second source of trouble. Felt needs a drip trim and well-dressed laps. EPDM needs clean, properly adhered upstands and fixings through the right trims. Where the garage meets the house wall, a flashing is chased in or fixed with a counter-flashing so rain cannot track behind.
Finally, water leaving the roof has to go somewhere. A blocked or missing gutter soaks the edge and lifts the covering. If a roof is already letting water in, our page on broken asbestos garage roof sheets applies where the old covering is sheet rather than felt.
Insurance, survey and the written quote
A new covering does not change who pays when the roof fails. Cover for outbuildings varies by policy, and our page on whether a garage roof is covered by home insurance explains how insurers look at wear and tear against sudden damage. Your insurer makes the decision on any claim, and complaints about that decision go to the Financial Ombudsman Service.
We start the survey by photographing the deck, the edges and the wall junction. Your written quote then gives a single total for only the work the fault demands. A written ten-year guarantee covers the workmanship, and the old covering leaves with us. Send pictures by WhatsApp, use the form or ring 01793 626096. Other options are on our garage roof replacement page.