Signs You Need a New Garage Roof (And When a Repair Will Do)
- Daniel Cunliffe
- 1 day ago
- 5 min read
Your garage roof doesn’t need to be pouring water before it’s classed as “bad.”
Small cracks, pooling water, or damp smells are often early warnings that your roof’s protective layer has failed. Catching these signs early can save you hundreds in repeated patch-ups or water damage.
If your garage roof is over 15 years old and showing two or more of these signs, plan for replacement rather than more patches.
This guide breaks down the key signs your garage roof needs replacing, how to spot them safely, and when a simple repair might still do the job.
Key Takeaways – Spotting Garage Roof Problems Early
Persistent leaks, ponding, or sagging are signs your roof covering has failed.
Felt roofs rarely last beyond 10–15 years in Lancashire’s weather.
Rubber (EPDM) and fibreglass (GRP) systems last 30–40 years with minimal maintenance.
Small cracks or loose flashing can lead to rot if left unchecked.
Once repairs start costing £600+, a full replacement is usually the smarter option.
💡 Tip: Inspect your garage roof twice a year - ideally after winter and again after heavy rain.
Visible Warning Signs
Most garage roofs don’t fail overnight - they give you clues first. From small cracks to standing water, these early signs are easy to miss but quick to spot once you know what to look for.
Here’s how to tell when your garage roof might be reaching the end of its life.
Water Leaks or Stains
Any damp patches on the garage ceiling or upper walls are a giveaway. Even faint brown marks can mean water’s getting in through small cracks or seams.
Pooling Water
Flat roofs should drain completely within 24–48 hours. Standing water after rain shows the slope or structure has sagged.
Cracks, Blisters, or Frayed Edges
Felt and GRP roofs naturally expand and contract - over time, this causes splits, blisters, and peeling edges. Once water gets beneath the surface, rot begins.
Moss, Algae, or Plant Growth
A green film or moss clumps hold moisture, which accelerates surface breakdown. It’s particularly common on shaded, north-facing garages.
Loose Flashing Around Edges or Walls
Metal flashing around joins or upstands can corrode or come loose. If you notice rust, gaps, or lifted edges, water can track behind and soak into the structure.
Hidden or Subtle Red Flags
Some issues aren’t obvious until you look closer - or start smelling them.
Musty, damp odours: trapped moisture beneath the roof deck.
Soft decking: feels spongy when stepped on (sign of rot).
Falling debris in gutters: granules or membrane fragments mean the top layer’s deteriorating.
Visible daylight: if you can see light through roof joints or edges, the surface is compromised.
Condensation build-up: inside a garage with no heating, often mistaken for damp - actually from poor roof insulation.
Fraying or lifted edges at upstands (where the roof meets walls)
Hairline cracks around pipes/vents that widen after frost
Rust marks or staining where flashing meets brickwork
Quick DIY Checks (Before Calling a Roofer)
You don’t need to climb onto the roof to assess its health. These three checks can be done safely from ground level:
After rain, look for pooling: any shiny, standing water means poor drainage.
Inspect gutters and downpipes: check for bits of felt, rubber, or grit - all signs of surface wear.
Look up inside with a torch: any small damp circles or mildew near the corners? That’s a leak path starting.
If you spot two or more of these symptoms, it’s worth booking a professional inspection before things worsen.
Safety note: Don’t climb onto the roof. View from the ground, a window, or inside the garage. If in doubt, book a professional inspection.
When a Repair Might Still Work
Not every leak demands a full re-roof. Repairs can be effective if:
Damage is limited to one small area
The roof is under 10 years old
There’s no visible sagging or soft decking beneath
Typical repair costs range from £250–£600 for felt or £350–£800 for rubber or fibreglass patching.
If your roofer quotes above that, it’s often better value to replace entirely.
When It’s Time for a Full Replacement
You’re likely past the repair stage if:
Cracks or blisters keep returning after patching
Water pools after every rainfall
Roof feels soft or uneven when walked on
Decking or joists show signs of rot
Repairs have been made more than once in two years
💡 Rule of thumb: once multiple repairs fail or the roof is over 15 years old, replacement is the only reliable long-term option.
Local Insight – Why Lancashire Roofs Fail Faster
Here in the North West, constant rain, frost, and leaf build-up make garage roofs wear out faster than in most parts of the UK.
We see this every week across Bolton, Rochdale, Bury, and Clitheroe - especially with older felt roofs that flatten and start pooling over time.
A recent job in Rawtenstall involved replacing a 14-year-old felt roof that had cracked in several places. The new EPDM system cost £1,350 and came with a 20-year guarantee - a clear example of long-term value over repeat patching.
5-Minute Garage Roof Health Check (Do This Week)
You don’t need a ladder or tools to get a quick idea of your roof’s condition. A few simple checks can reveal a lot:
After rainfall: look for shiny, standing water - it means the slope isn’t draining properly.
Check gutters and downpipes: any bits of felt, rubber, or grit are early signs the surface is breaking down.
Walk inside with a torch: look for brown rings, dark streaks, or musty smells near the ceiling.
Scan the edges: make sure flashing isn’t lifting or rusting where the roof meets the wall.
If you spot two or more of these warning signs, your roof is likely due a professional inspection - and possibly replacement. Acting early prevents leaks, rot, and far higher repair bills later.
FAQs – Garage Roof Damage & Replacement
Still unsure what counts as “normal wear and tear” versus real trouble? These quick answers cover the most common questions we hear from Lancashire and Greater Manchester homeowners about garage roof repairs, replacements, and maintenance.
How often should a garage roof be replaced?
Usually every 20–25 years, depending on material and exposure.
Can you just overlay new felt on old felt?
Not recommended - it traps moisture and shortens lifespan. Always remove the old layer and inspect the decking first.
Is replacing a garage roof messy?
A good roofer will remove all old materials, clean the area, and dispose of waste safely.
What’s the cheapest long-term option?
Felt is cheapest to install, but rubber (EPDM) lasts twice as long and rarely needs repair.
Will a new roof reduce condensation?
Yes – especially if insulation boards are added beneath. Proper ventilation and insulation make a huge difference.
Do I need planning permission?
No – most garage roof replacements fall under permitted development unless you’re altering the roof height or type.
How long does it take to reroof a garage?
Most single garages take 1–2 days; complex access or decking repairs can add time.
What’s the most expensive part of replacing a garage roof?
Usually materials (EPDM/GRP vs felt) and any timber/decking repairs. Scaffolding and waste disposal can also add to the total on awkward sites.
How much does it cost to fix a sagging garage roof?
Sagging often means decking or joists need repair, not just a new covering. Costs vary by damage and size - budget for a survey so we can price structural fixes accurately.
Local Garage Roof Inspections & Replacements
From Accrington and Blackburn to Preston and Manchester, Daniel Roofing & Guttering repairs and replaces garage roofs that have seen better days.
We work with high-quality felt, fibreglass, and rubber systems - all installed with clear pricing, tidy workmanship, and written guarantees.
If you’ve spotted two or more of the signs above, it’s time for a professional look.
Call 07922 564912 or learn more about our garage repair and replacement services to book your free inspection today.
