How to repair a flat garage roof

Garage roofs take a beating — rain, frost, heat, falling debris, and years of wear.

So if your garage roof has started leaking or cracking, and you’re searching

“how to repair a flat garage roof?”

This guide will show you exactly what to look for and what your repair options really are.

Flat garage roofs in the UK are usually made from:

•EPDM rubber

•GRP fibreglass

•Torch-on felt (older systems)

Each one needs a different repair method, and some are much better long-term than others.

Let’s break it down.

*. Identify Your Garage Roof Material

Before repairing anything, you must know what system you have:

EPDM Rubber Garage Roof

Smooth, flexible, single sheet

Common problems: splits, punctures, loose edges

GRP Fibreglass Garage Roof

Hard, slightly textured surface

Common problems: cracks, pinholes, topcoat wear

Felt Garage Roof

Rough, layered appearance

Common problems: blistering, cracks, lifted joints

Different roof types need different repair products.

*Look for the Source of the Problem

Garage roof leaks usually come from:

•Splits in the membrane

•Cracks in fibreglass

•Blistering in felt

•Loose trims or edges

•Perished joints

•Damage from UV exposure

•Ponding water

•Poor installation years ago

Understanding the cause prevents the same leak from returning.

*How to Repair an EPDM Garage Roof

EPDM (rubber) is one of the easiest flat roof materials to repair — when done correctly.

Repair steps:

1.Clean the damaged area

2.Apply EPDM primer

3.Cut and apply a rubber patch

4.Roll it flat and seal the edges

5.Let it cure

EPDM repairs are strong and long-lasting when done with correct materials..

*How to Repair a GRP Fibreglass Garage Roof

GRP is durable but needs a proper resin-based repair — NOT silicone or quick-fix products.

Repair steps:

1.Sand the crack or damaged area

2.Clean with acetone

3.Apply fresh GRP resin

4.Add fibreglass matting for reinforcement

5.Apply more resin

6.Finish with a new topcoat

This restores the strength and waterproofing of the roof.

*How to Repair a Felt Garage Roof

Felt roofs are common on older garages but are the least durable.

Repair steps:

1.Slice open blister to release moisture

2.Heat and bond the felt back down

3.Apply bitumen adhesive

4.Add a felt patch

5.Seal edges

Felt repairs work short-term but usually indicate the roof is near the end of its lifespan.

*When NOT to Repair a Garage Roof Yourself

Leave it to a professional if you notice:

✘ Soft or rotten decking

✘ Large splits across the roof

✘ Water trapped under the membrane

✘ Damage covering more than 20–30% of the roof

✘ Repeated leaks

✘ Wrong materials used previously

DIY repairs often make problems worse if the issue is deeper than the surface.

*How Much Does It Cost to Repair a Flat Garage Roof?

💷 Flat Garage Roof Repair Cost: £120 – £500 (maximum)

Breakdown:

•Minor EPDM repair: £80–£150

•Medium repair: £150–£300

•Large section repair: £300–£500

Anything beyond this normally means the roof is failing and may need replacement.

*When Is It Better to Replace the Garage Roof?

Replace your garage roof if:

•It’s over 20–25 years old

•Felt is cracking everywhere

•The roof deck is soft or sagging

•Multiple leaks keep appearing

•Repairs are becoming frequent

Most homeowners upgrade old felt to EPDM or GRP for reliability and longevity.

*Need Your Garage Roof Repaired?

Correct Way Roofing specializes in flat garage roof repairs across Telford and the West Midlands.

We offer:

✔ Repairs for EPDM, GRP, and felt

✔ Max repair cost of £500

✔ Emergency leak repairs

✔ Free inspections

✔ Guaranteed workmanship

✔ Local, family-run roofing specialists

📞 Call Correct Way Roofing for a free on-site inspection and honest price estimate.

Call Us Today