In short
Repair a flat roof when the covering is sound and the problem is one thing: a split at a joint, a blocked outlet, a lifted flashing. Replace it when the felt is blistered or cracked across the surface, the deck feels soft underfoot, or it has been patched more than once already. MyJobQuote's 2026 guide gives felt 10 to 25 years and EPDM 25 to 50, so a felt roof past twenty is usually a replacement whatever the leak looks like.
This is a job for our Flat roof (EPDM) service.
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The quick test
Walk on it, carefully, on a dry day. If it is firm everywhere and the problem is in one place, it can probably be repaired. If it gives anywhere, or there is standing water that never drains, or the surface is crazed like a dried-out riverbed, the covering has finished and the deck may be going with it. We see a lot of the second kind on garages and extensions around King's Lynn and Wisbech that were felted in the eighties and nineties.
Repair makes sense when
- The felt is under about fifteen years old and otherwise flat and sound.
- The leak is at a detail: an upstand, an outlet, a pipe, a flashing to the house wall.
- The deck is dry. We check from below where we can, and by feel from above.
- You are selling, or the building is coming down in a few years, and you need it dry not perfect.
Replacement makes sense when
- The covering is blistered, cracked or bald across the surface rather than in one spot.
- It has already been patched. A patch on a patch fails at the edge of the old patch.
- The deck is soft, or the ceiling below is stained in more than one place.
- The roof ponds. Standing water on felt shortens its life and the fix is a new deck laid to a fall, not a patch.
| Option | What you get | Life (MyJobQuote 2026) |
|---|---|---|
| Repair felt | The same roof, dry at that point | Whatever is left of 10–25 years |
| New felt | New covering, seams and all | 10–25 years |
| New EPDM | One sheet, no seams, new deck if needed | 25–50 years |
Why we lean towards EPDM when replacing
Felt fails at its seams and at the details. Firestone's RubberGard EPDM comes in sheets large enough to cover a domestic roof in one piece, so there are no seams to fail, and the manufacturer's published life expectancy is more than 50 years even in full sun. It can also be repaired with hand tools if it is ever damaged, which is not true of a fibreglass roof once it has cracked.
The regulations point
The Planning Portal's re-roofing guidance says replacing a flat roof that has integral insulation may mean upgrading that insulation. A repair does not trigger that; a replacement over a heated room usually does. It is one more cost on the replacement side, and one more reason to do it once, properly, rather than patch it three times and then replace it anyway.
