Flat roof repairs that actually last

Flat roof repair is a diagnosis job before it is a labour job. The visible fault, a blister, a damp patch on the ceiling below, a pond that never dries, tells a roofer whether the covering has a local injury or has started to fail as a whole. Get that call right and a modest patch lasts for years; get it wrong and you pay for the same square metre again every winter.

The faults we see most

• Blistering: air or moisture trapped under the covering lifts it into bubbles. One blister is patchable; blistering across the roof means the felt itself has broken down. The failing felt roof guide shows the difference.
• Splits and cracks: movement, frost and age open seams and stress points, letting water straight through to the deck.
• Ponding: water that sits for days accelerates wear and finds every weakness. Persistent ponds usually mean the falls need correcting, not just the covering patching; see the flat roof ponding guide.
• Failed joints and details: lifted laps, cracked upstands and flashings where the roof meets a wall, the most common leak points on any flat roof.

How a proper repair is done

1. Find the real entry point. Water travels along the deck before it shows indoors, so the stain rarely sits under the hole.
2. Dry and prepare the area. No patch bonds to a wet, dirty or chalking surface.
3. Repair with the same system. Torch-on felt patched with felt, EPDM with bonded rubber, GRP re-laminated and top-coated. Generic sealant over any of them is a bodge that fails within seasons.
4. Check falls and outlets. If ponding caused the failure, patching without correcting the drainage just schedules the next leak.
5. Photograph and guarantee the work. In writing, like any other roofing job.

What flat roof repairs cost

Full pricing across felt, EPDM and GRP is in the flat roof cost guide, with felt-specific repair and re-covering prices in the felt roof cost guide.

Repair or replace?

The pattern of the damage decides it. One split, one blister or one lifted joint is a local injury: patch it and move on. Bubbling, crazing or cracking spread across the surface means the material itself has oxidised and gone brittle, and every patch simply moves the next failure a metre sideways. At that point, put the money into a new covering instead: our flat roof replacement page covers strip-and-renew, insulation upgrades and what a proper job includes.

Why use a vetted roofer

Flat roof repairs are cheap enough that many homeowners take the first quote, which is exactly how mastic-over-the-crack merchants stay in business. Every roofer in the Expert Roofers network is vetted for insurance, trading history and real customer feedback, diagnoses before pricing, and repairs with the same system the roof is built from.