Repairing a garage roof involves identifying the leak source, clearing debris, and applying appropriate fixes based on your roof type. For felt roofs, use waterproof cement on small holes. For EPDM rubber, apply self-adhesive patches. Metal roofs need corroded screws replaced and mastic applied to gaps. Most minor repairs can be completed by homeowners in a few hours, though serious damage like rotted timbers or asbestos requires professional help.
Garage roofs often go unnoticed until something goes wrong. At Checkaroof, we hear from homeowners every week who've spotted water stains, felt a damp smell, or noticed daylight peeking through joins. These small signs usually mean bigger problems are brewing underneath, which is why knowing how to repair a garage roof early can prevent costly damage.
What makes garage roof repair different from your main house is simple. Most UK garages were built with flat or low-pitch roofs using lightweight materials chosen for cost rather than longevity. Between the 1960s and 1990s especially, builders focused on practicality. The result? Many of these roofs are now hitting their limit.
A surprising number of UK garages need repairs because they don't get the same attention as the main house. We don't climb up there to check. We don't clear the gutters twice a year. Small cracks develop, felt lifts at the edges, and moisture starts to seep through.
Standing water is the main culprit on flat garage roofs. Heavy rainfall pools instead of draining, and over time that water works its way into cracks and blisters in the covering. Strong winds lift edge trims and flashing, letting rain track underneath even when the surface looks fine from below.
Moss and debris pile up faster than you'd expect, particularly in northern and coastal areas. Left unchecked, this organic matter holds moisture against the roof, speeding up deterioration. Then winter arrives. Freeze and thaw cycles turn small splits into bigger tears. By spring, what could have been a quick fix becomes a replacement job.
Before you grab any tools or materials, you need to know where the leak starts. Water rarely drips straight down from the damaged spot. It travels along roof timbers or rafters, sometimes ending up metres away from the actual problem.
Start inside the garage. Look for water stains or damp patches on the ceiling. Check the walls near the floor for discoloration on wood or concrete. These marks tell you where water is ending up, not where it's getting in. Water leaking through the roof often shows up as mould growth on the underside of the roof deck or along the edges where timbers meet the walls.
Now head outside. Inspect the edges and joints of the roof where felt may have lifted. Check around anything that penetrates the surface, like vents or pipes. Examine the flashing where the roof meets the walls. Gaps in the brickwork can also let water through.
A leaking garage roof can cause more damage than you might think. Mould spreads quickly in damp conditions, especially in garages with poor ventilation. If you spot black or green patches on the underside of your roof or on stored items, that's a clear sign that water leaking has been happening for a while.
Estate agents and surveyors flag ageing garage roofs during property sales all the time. Sellers often discover leaks they didn't know existed when a professional takes a closer look. If you're planning to sell, getting ahead of these issues saves time later.
Safety comes first when working at height. Use a sturdy ladder positioned at a 75-degree angle. Wear non-slip shoes, gloves, safety glasses and a hard hat. If the roof is sagging or you spot rotted timbers underneath, stop. These need professional structural repair, not DIY patches.
Move valuable items out of the garage before you start. Even temporary repairs can disturb dust, and you don't want tools or equipment getting wet if rain arrives unexpectedly.
Check what type of roof you have. Felt, EPDM rubber, metal panels and fibreglass GRP all need different approaches. Using the wrong material or method wastes time and money.
Never apply sealants, coatings or adhesive tapes to a wet roof. They won't bond properly. Wait for a dry spell and give the surface time to dry completely.
Small holes in felt roofs are straightforward to fix. Apply waterproof roofing cement or mastic directly to the damaged area. Press it down firmly and smooth the edges so water can't get underneath.
For cracks, use a heavy-duty waterproof tarp as a temporary cover before rain arrives, or apply bitumen mastic and roofing tape to seal the split. This buys you time if you can't complete a full repair immediately.
Larger cracks need more attention. Clean the surface first. Remove debris, moss and algae so repair materials bond properly. Then apply a layer of solar-reflective coating and embed fibreglass mesh scrim into it. This reinforces the repair and helps prevent the crack from spreading.
If your garage flat roof has multiple damaged areas or the felt is lifting in several places, patching becomes less effective. At that point, replacement makes more sense than repeated short term fixes. When a leaking garage roof has deteriorated beyond simple repairs, installing a new roof might be the only proper solution.
EPDM roofing is known for lasting over 50 years when installed correctly. Repairs are usually simple because the material is flexible and resilient.
For damaged areas, use a self-adhesive EPDM patch or cover tape. Clean the surface first, making sure it's completely dry. Press the patch down firmly, working from the centre outwards to avoid trapping air bubbles.
EPDM garage roof kits are designed for DIYers and contain everything needed in the right quantities. Installation typically requires few tools and is often completed in a single sheet using cold applied adhesives. This makes it a popular choice when homeowners want to replace an entire garage roof themselves.
Metal roofs develop different problems. Screws work loose over time, creating gaps where water can enter. Panels can corrode, especially older galvanised steel that's lost its protective coating.
Replace corroded screws first. Then apply metal-compatible mastic to screw holes or gaps between panels. Make sure the mastic is designed for the material you're working with.
If the panels themselves are heavily corroded or cracked, replacement is usually cheaper in the long run than ongoing repairs. Galvanised steel roof panels are durable and cost-effective, making them a solid option for garage roofs.
Some garage roof repairs are beyond DIY capability. Asbestos sheets were common in older garages, and you should never attempt to remove or repair these yourself. The health risks from fibres are serious. Only trained professionals with proper protective equipment should handle asbestos, and it must be disposed of according to regulations, which is why using a reputable roofing company is essential.
If you're not confident working at height, hire a roofing contractor. A fall can cause serious injury, and no repair is worth that risk.
When leaks are seriously affecting how you use the garage, or when damage is too extensive to patch, professional replacement becomes necessary. We recommend gathering two to three quotes from reputable firms to understand what you can expect to pay.
Signs you need a professional include visible rot in the roof structure, large sections of missing or damaged material, or persistent leaking despite multiple repair attempts. If you're finding water leaking into the garage every time it rains, that's a clear indicator that patches won't be enough.
The price depends on how much work is needed and what materials you're using. Complete roof removal and replacement for a single garage can range from £1,000 to £1,800, depending on the size and amount of work required.
Repairs to felt and fibreglass materials cost approximately £20 to £80 per square metre. The type of repair work affects the final cost.
Liquid roofing products for temporary repairs run between £50 and £100 for a 5kg tub. These can be useful for buying time until you can arrange a full repair.
When comparing quotes, make sure contractors include disposal costs if old materials need removing. Asbestos disposal adds to the total, as does scaffolding if your garage is difficult to access, all of which factor into calculating how much to repair a garage roof.
Many years of trouble-free service come from basic upkeep rather than expensive repairs. Clear guttering and downpipes regularly to prevent water backing up onto the roof surface. Blocked drainage causes water to pool, which leads to leaks.
Walk around the garage every few months and check for debris, moss or algae building up on the surface. A quick sweep now prevents bigger jobs later.
Look at the edges and any points where different materials meet. These are where problems often start. Fill small gaps before they become cracks. Plug holes before water can seep through.
Check the underside of the roof from inside the garage during your inspections. Look for any signs of mould, damp patches or water stains that might indicate a slow leak developing. Catching these early prevents the need for a new roof down the line.
If you're converting a garage into a gym, workspace or storage area that needs to stay dry and warm, consider upgrading the entire roof. Modern membrane systems handle UK weather conditions better than older materials and require less maintenance over time.
Some homeowners use repairs as a chance to install something more durable. Premium roofing membranes are popular because they avoid the need for repeated fixes every few years, making them a top consideration when choosing the best roofing material for garages.
High-performance single-ply membranes like Sarnafil have become increasingly common across the UK for flat garage roofs. They offer strong weather resistance and a clean, modern appearance that suits contemporary garden rooms and garage conversions.
Advanced membrane systems are often lighter than traditional multi-layer felt builds. This makes them suitable for older garage structures where adding weight could be a concern.
Fibreglass GRP is another common material for garage flat roofs. It creates a seamless, waterproof surface that's tough enough to walk on for maintenance.
The choice between patching and upgrading often comes down to how you use the space. Storage-only garages might get temporary fixes, while converted spaces usually get full upgrades that protect electrical installations and insulation.
Remove all loose material before applying any sealant or adhesive. If the surface isn't clean and dry, the repair won't stick properly.
Use materials designed for your specific roof type. Adhesives formulated for EPDM won't work on metal, and felt roof repairs need different products than fibreglass.
Work in dry weather with temperatures above 5°C. Cold or damp conditions stop most roofing materials from bonding correctly.
Don't rush. Taking time to prepare the surface and apply materials carefully means the repair will hold for many years instead of failing in the next storm.
If you notice condensation forming inside the garage, improving ventilation might solve water problems without any roof work. Condensation can cause water ingress more often than actual leaks, particularly in garages used for storage where air doesn't circulate well.
Repeatedly patching the same roof becomes expensive. If you're applying a new fix every year, calculate what you're spending. A full garage roof replacement might cost less over five years than ongoing repairs.
Look at the overall condition. If more than 30 percent of the surface is damaged, replacement usually makes financial sense. Modern materials last longer and need less attention, which saves you time and hassle.
Garden rooms and garage conversions are driving more interest in durable, low-maintenance coverings. If you're upgrading how the space is used, upgrading the roof at the same time protects your investment.
We help homeowners across the UK make these decisions every week. Our advice is always the same. Fix it properly once rather than patching it repeatedly. Your garage roof protects everything underneath, from your car to your tools to your storage space. Treat it with the same care you'd give the main house roof.
Garage roofs are one of the most commonly repaired roofing elements in the UK because they're exposed to the elements yet often overlooked during routine maintenance. A surprising number of leaks start around roof edges, upstands or joints rather than the centre of the roof surface itself.
Many homeowners only discover damage when upgrading garage doors or installing insulation. These hidden problems can go unnoticed for years until something forces a closer look.
At Checkaroof, we're here when you need help. Whether you're tackling a small repair yourself or need professional advice on replacement options, we provide the information and support to keep your garage dry and functional.
If you'd like to discuss your garage roof with our team, visit our website and fill out the contact form. We'll get back to you with honest advice tailored to suit your specific situation.
