Roof Felt Repair: Cost & When to Replace (UK)
Felt is a common, cost-effective roof covering, but it does not last forever. In 2026, roof felt repair costs £150-£600 for a patch or small area, while a full flat-roof felt replacement runs £1,200-£2,500 for a typical garage or extension roof. Repairs to under-tile (sarking) felt depend on access and how many tiles must come off. This guide covers repair versus replace, torch-on felt versus modern EPDM, and what drives the cost.
Roof Felt Repair Cost & Options
"Felt" covers two very different jobs: the waterproof layer on a flat roof (torch-on or bitumen felt), and the underlay beneath tiles on a pitched roof. Cost depends on which, the area affected, and access. Here is what to expect and when a full replacement makes more sense.
Flat roof felt patch repair
£150-£600. Sealing a split, blister or lap on a small area of torch-on felt. A short-term fix on an ageing roof; sensible on a sound one with localised damage.
Full flat roof felt replacement
£1,200-£2,500 for a typical garage or single-storey extension roof. Strip, re-board if needed, and lay new torch-on felt with fresh trims and drainage.
Under-tile (sarking) felt repair
Varies with access. Replacing torn underlay means lifting tiles or working from the eaves; small areas £200-£600, larger sections more if scaffolding is needed.
Torch-on felt vs EPDM rubber
New felt is cheapest upfront (15-25 year life). EPDM rubber membrane costs a little more but can last 30-50 years with fewer seams - often better value on a full replacement.
What drives the price
Area, roof height and access, whether the deck/boarding is rotten (re-boarding adds cost), the number of upstands and outlets, and scaffolding for anything above single storey.
When to replace not repair
If felt is widely cracked, blistered or ponding, or you are patching repeatedly, a full replacement (felt or EPDM) is more cost-effective than chasing leaks.
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