Garage Roof Replacement Cost: Full UK Price Guide

Garage roof costs by material

The material you choose is the single biggest factor in the cost. Here's what each option costs for a standard single garage (roughly 3m x 5m = 15m²):

Prices include labour, materials, and VAT for a standard single garage (approximately 15m²). Prices based on 2026 UK averages. Double garage costs are typically 50–70% more.

Felt: cheap but you get what you pay for

Most garage flat roofs in the UK are covered in roofing felt. It's been the standard for decades because it's cheap and quick to apply. A three-layer torch-on felt system costs £500–£800 for a single garage.

The problem? Felt doesn't last. Even a good three-layer system will only give you 10–15 years before it starts cracking, blistering, and letting water in. If your felt roof has already failed once, replacing it with more felt is throwing good money after bad. You'll be doing it again in a decade.

The one scenario where felt makes sense: if you're selling the house soon and just need a quick, cheap fix. Otherwise, spend the extra £300–£400 and get EPDM.

EPDM rubber: the sweet spot

EPDM (ethylene propylene diene monomer — nobody uses the full name) is a synthetic rubber membrane that's become the go-to choice for flat roofs. It comes in a single sheet, which means no joins and no weak points where water can get in.

At £800–£1,200 installed for a single garage, it costs only slightly more than felt but lasts 30–50 years. It handles UV exposure, temperature extremes, and standing water without degrading. Most EPDM manufacturers offer 20–25 year guarantees.

It's also the most DIY-friendly option if you're handy. Firestone and ClassicBond sell kits for about £300–£500 in materials for a single garage. The installation involves gluing the membrane to the roof deck and sealing the edges — no specialist tools or flame required.

Fibreglass (GRP): the premium flat roof

Fibreglass — technically glass-reinforced polyester — creates a seamless, rigid surface that's essentially waterproof from day one. It's tough enough to walk on, which makes it popular if you use the garage roof for anything (though you shouldn't stand on it regularly without proper reinforcement).

At £1,200–£1,800 installed, it's the most expensive flat roof option. It also needs dry, warm conditions to cure properly — so winter installations can be tricky. If it's done badly (wrong resin mix, rushed application), GRP can crack. Always use a specialist flat roofing company registered with the National Federation of Roofing Contractors (NFRC), not a general builder.

When to repair vs replace

Not every leak means a full replacement. Here's a rough guide:

• Small patch repair (one leak, otherwise sound): £100-£250. Worth doing if the rest of the roof is in good condition and under 10 years old.
• Re-felting over existing felt: £300-£500. Only worth it if the deck underneath is sound. If the timber is damp or rotten, you need a proper strip and replace.
• Full replacement needed when: the felt is cracked and blistered across most of the surface, the timber deck feels soft or spongy, water pools on the roof and doesn't drain, or you've already patched it multiple times.

One thing to watch out for: if the timber deck (the boards the membrane sits on) is rotten, that adds £400–£800 to the cost. Any decent roofer will check this before quoting, but make sure it's included in the price if needed.

Flat to pitched: is it worth the upgrade?

Converting a flat garage roof to a pitched roof costs £2,500–£5,000 — roughly double the cost of a flat roof replacement. Under permitted development rules, a like-for-like replacement or a change from flat to pitched usually doesn't require planning permission. So is it worth it?

If you're planning to convert the garage into living space (home office, gym, extra bedroom), a pitched roof makes sense. It gives you more headroom, better insulation potential, and it'll look right with the rest of the house. It also lasts much longer — 50+ years for tiles versus 30 for EPDM.

If the garage is staying as a garage (or a workshop, storage space, etc.), a pitched roof is overkill. A quality EPDM or GRP flat roof will keep it dry for decades at half the price.

How to save on a garage roof replacement

• Get at least 3 quotes. Prices vary significantly - we've seen the same job quoted at £700 and £1,400 by different roofers.
• Consider DIY for EPDM. If you're comfortable on a ladder and your garage is single storey, an EPDM kit saves £400-£700 in labour.
• Replace guttering at the same time. The scaffolding (or ladder access) is already there, so adding new guttering costs much less than doing it separately.
• Don't replace the deck if it's sound. Some roofers quote for a full deck replacement as standard. If the existing timber is dry and solid, you don't need new boards.
• Book in winter. Roofers are quieter November-February. EPDM and felt can be fitted in cold weather (GRP can't), so you may get better prices.

Frequently asked questions

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