How long does a garage roof last?

Most garages in and around Stroud carry either a flat membrane roof or a low-pitched sheet roof, so the useful comparison is between those coverings. The ranges below come from published guides and do not always agree with each other, so read each row as a band.

The spread is wide for a reason. Less adds that felt laid with care can last as long as 20 years, while a badly laid roof may be gone in under 10, so the quality of the laying matters as much as the material.

EPDM shows the widest gap. GreenSpec gives 20 to 30 years, the Building Centre calls it more than 25 years, while Less, updated in 2026, quotes 30 to 50. CORC puts well-maintained felt at 30 years or more. Differences like these come from what each source assumes: a sheltered roof or an exposed one, a continuous membrane or one full of joints, a deck in good order or one that moves.

For a garage, we would plan on the lower and middle part of any range, and treat the upper end as what a well-fitted, well-looked-after roof might reach. A manufacturer warranty is something else again. It covers a product for a fixed term and says nothing certain about how long your roof will last.

Garages are often neglected roofs. Nobody looks at them from upstairs, gutters fill with leaves, and branches overhang. Each of these hurts a flat roof in a different way.

Ponding and poor falls

A flat garage roof needs a fall so water leaves it. BS 6229, as quoted by IKO and Rockwool, designs for 1:40 so that the finished roof still falls at 1:80 or better. Where the deck sags, water sits, and standing water ages a membrane faster than running water does.

Edges, upstands and penetrations

Most leaks start where the membrane stops: the drip edge, the upstand against the house wall, a vent or a rooflight kerb. A good membrane with a poor detail fails at the detail. These are the places we photograph first.

Debris and shade

Leaves, moss and a blocked outlet keep a roof wet. Trees overhead add all three. Clearing the roof and the gutter once or twice a year costs little and extends the life of nearly every covering. A garage that backs onto a bank, a hedge or a neighbour's tree needs that sweep more often than one standing in the open.

Foot traffic is the other quiet killer. Every trip up for a gutter, an aerial or a satellite dish risks a scuff or a puncture in a membrane that is only a few millimetres thick, so lay a board and keep visits rare.

A published lifespan only suggests when to begin watching. The roof itself tells you more. From inside the garage, look at the ceiling or the underside of the deck in daylight. Brown tide marks, damp timber, light showing through and a musty smell all point to water getting in. Outside, look for blisters, splits or lifting laps in felt, wrinkles or loose edges in EPDM, and cracks or crazing in GRP.

On the roof surface, standing puddles that are still there a day after rain suggest the falls have failed. Moss mats, a blocked outlet and cracked edge trims are cheaper to fix than a whole covering, so catching them early can add years. Take photographs each year from the same spot. A series of dated pictures shows whether a fault is growing, and it is useful evidence whichever way the decision goes.

Many older garages have corrugated sheet on a shallow pitch. A cement sheet roof lasts as long as its fixings, laps, ridge and exposure allow, so inspect it rather than counting years. Sheet roofs tend to fail at the fixings, the laps and the ridge before the sheet itself gives out, and that brittleness increases with age. If the sheeting could be asbestos cement, treat that as the first question; see our answer on spotting asbestos on a garage roof.

Whatever the material, a roof that has outlived its quoted range is not automatically failing. It is a prompt to inspect it more often, looking at the underside from inside the garage for stains and daylight.

Cost per year of life is a fairer comparison than price alone. A cheaper covering that lasts half as long is not saving anything over the long run, though a garage you plan to demolish or convert does not need a 30-year roof. Our guide to garage roof materials compares all the options, and felt or EPDM for a garage roof puts the two most common head to head. Whether a roof failure is covered by your policy is a separate question, covered in is a garage roof covered by home insurance.

Our page on garage roof replacement in Stroud covers the work. After a survey that records your own roof in photographs, you get a written quote. Waste leaves with us, and the finished roof carries a 10-year workmanship guarantee in writing.