The short answer
A flat roof typically lasts 10 to 20 years if it is felt, 20 to 30 years or more if it is EPDM rubber, and 25 to 40 years if it is GRP fibreglass. Lead and zinc can last far longer. These are published typical ranges, not promises, and standing water, a wet deck, poor details and neglect all cut them short.
Typical lives by material
Published figures vary, and sources disagree, so treat the ranges below as typical rather than guaranteed. Each depends on exposure, workmanship and maintenance.
| Covering | Typical life | Note |
|---|---|---|
| Torch-on felt | 10 to 20 years | Top end needs multi-layer work |
| EPDM rubber | 20 to 30 years or more | Sources range up to 50 |
| GRP fibreglass | 25 to 40 years | Needs a stable deck |
| Single-ply PVC | 20 to 30 years | Depends on the product |
| Zinc | 60 to 100 years or more | Maker says over 100, nearer 60 on severe sites |
| Lead sheet | 50 to 100 years | Properly laid |
The figures come from trade and cost guides such as GreenSpec, Less and the Confederation of Roofing Contractors, and, for zinc, from HomeBuilding and the maker VMZINC. A manufacturer's guarantee is a guarantee and not a lifespan, so we never read it as one.
Why one felt roof fails in ten years and another lasts twenty
Felt is the covering with the widest spread. Less, a cost guide, reckons on 20 years for a good felt job and under 10 for a poor one. CORC, the Confederation of Roofing Contractors, puts a well-maintained felt roof at 30 years or more. The difference is craft: how well the deck was prepared, how many layers went down, how the laps were sealed and what finish protects the top layer.
Bitumen is softened by heat and hardened by cold, so the surface slowly loses its oils. Sunlight and ponding speed that along. A mineral finish on the cap sheet shields the bitumen from ultraviolet light, and when the chippings wear away the surface ages quickly.
The same logic applies to every covering. The material sets a ceiling, and the installation decides how close to it the roof gets. For a longer comparison of the materials themselves, see our guide to flat roof materials.
What shortens a flat roof's life
A handful of causes account for most early failures.
- Standing water. Water that stays on the surface speeds up ageing and finds weaknesses in laps and seams.
- A damp or rotten deck. If the timber beneath is wet when the covering is laid, or becomes wet through a leak, the deck can distort and the covering splits above it.
- Poor edge details. Low upstands, loose trims and unsealed flashings let water behind the covering.
- Foot traffic. Repeated walking scuffs felt and punctures rubber.
- Blocked outlets and gutters. Debris holds moisture and sends water where it should not go.
- Condensation. Moist air from the room can condense inside a cold roof and rot the structure from within.
None of these is a surprise to a roofer. Most are preventable, which is the point of the routine described in flat roof maintenance.
Signs the end is near
A flat roof signals its decline in recognisable ways, and the pattern matters more than any single sign.
Widespread cracking or crazing, bare areas where the surface has worn through, laps that will not stay stuck down and patches on top of earlier patches all point to a tired covering. Repeated leaks in different places suggest the whole membrane is failing, not one spot. A soft or spongy feel underfoot, if anyone has to go up, can mean the deck has absorbed water.
Inside, damp patches that return after each repair are the most telling sign. One repair that holds is a repair. Several that do not are usually the roof telling you something. Our page on repair or replace turns those signs into decision rules, and the page on flat roof problems covers the faults themselves.
Getting the most from a new roof
The best time to influence a roof's life is when it is laid. Falls that drain properly, a dry and sound deck, enough insulation placed to avoid condensation, upstands of sensible height and trims fixed firmly all add years. They are also hard to correct later without stripping the roof.
When a roof is replaced, we check and repair the deck, and we put the details right as part of the job, not as an afterthought. Matching the covering to the use matters too, so a roof that will be a terrace is built for foot traffic from day one.
The final element is care. Clearing the roof and checking it twice a year costs very little against the price of a new covering, and it is the one factor in the owner's control.
What a replacement costs against a repair
Replacement is typically £2,800 to £7,500 for a flat roof, according to MyBuilder (2026), with per square metre ranges of £70 to £100 for felt, £90 to £130 for EPDM, £95 to £150 for GRP and £150 to £200 or more for lead. They are national figures from a cost guide, and not Empire prices.
A small repair costs a fraction of that, which is why a local fault on a young roof is worth repairing. When an old roof has failed across its whole surface, repairing it repeatedly can cost more than renewing it. For a view of your own roof, we survey free of charge, and the fixed price in writing follows. The flat roofing service page lists the rest of what we do.
One more point for owners weighing up an old roof: the lives quoted above are for the covering alone. The deck, the insulation and the edge details have their own lives, and a covering that is still sound can sit on a deck that is not. So we look at the layers below as well as the surface, and why we lift a corner or open a core where the roof allows it.
