Written by the Compton Roofs team — a family-owned and managed concrete garage specialist. Our owner has 35 years’ hands-on experience of concrete garages, and our site work is carried out by time-served approved contractors who do this work all week, every week. Last updated: 11 September 2026
TL;DR: Concrete garages ask very little of their owners, which is exactly why they get forgotten about. A few minutes of attention a couple of times a year will add years to the building and will keep any structural guarantee intact. Clear the gutter and check the outlet is running; look along the ridge and eaves from the ground; paint exposed steel before rust takes hold; re-treat exposed timber annually; keep door gear lubricated and running true; let a floor dry properly before painting or lining, using dry heat rather than gas; and fit eaves and foam filler while a roof is being replaced rather than afterwards. If your roof is a corrugated cement type of an age that may contain asbestos, do not brush, drill, cut or pressure-wash it — leave it alone and call us.
Because it asks so little. A concrete sectional garage has no annual service, nothing that beeps at you and no obvious warning that anything is wrong until water is already inside. That is exactly why they get forgotten about, and why the faults we are called out to are almost always small faults that were left for several years.
A few minutes of attention a couple of times a year — spring and autumn is the natural rhythm — will add years to the building. It will also keep any structural guarantee intact: guarantees on buildings and on roof systems, ours included, assume the building has been kept clear of standing water and that exposed steel and timber have been maintained.
From 35 years in the trade: almost every “the garage is past it” call we take turns out to be a blocked gutter that has been overflowing down the same panel for five winters, plus a roof covering at the end of its life. Neither of those is the concrete. Look after the water and the concrete will outlive all of us.
Clear leaves and moss from the gutter and check that the outlet is running. Pour a bucket of water in at the far end and watch it leave; if it pools, the bracket line or the outlet is the problem, not the volume of rain.
Standing water is the single most common cause of stained panels, rotten fascias and damp inside. It is also the fault that costs least to put right and most to ignore.
| Check | What you are looking for | If it is wrong |
|---|---|---|
| Gutter run | Leaves, moss, silt, nesting material | Clear by hand, flush with water |
| Outlet and downpipe | Water leaving freely at the bottom | Rod or clear the outlet; check the shoe at the base |
| Gutter brackets and supports | Sagging sections, water sitting mid-run | Re-support the run — gutter support kits are stocked |
| Fascia behind the gutter | Staining, softness, swelling | Re-treat now, replace if the timber has gone |
| Panel below an overflow | Green staining, damp patch inside | Fix the overflow first, then let the panel dry |
Look along the ridge and eaves from the ground. You are looking for missing filler, lifted flashing or a loose fixing — any of which lets wind and rain in, and gets worse quickly, because once wind can get under a sheet line it works at it every gale.
You do not need to get on the roof to do this, and on a garage you should not. Stand at each corner and sight along the ridge line and the eaves line: both should be straight and continuous, with no daylight, no gaps where filler has perished, and no fixings standing proud. A pair of binoculars from the ground beats a ladder every time.
If you find water inside but the roof looks sound, consider condensation before you assume a leak — a cold uninsulated sheet drips onto everything below it, which is what anti-drip lining exists to prevent. Our guides to how long roofing felt lasts, corrugated garage roof sheets and why patching a leaking flat garage roof will not fix it explain what each older covering does at the end of its life.
From our fitters: a missing 300mm of ridge filler is a five-minute job on the day we are on a roof and a rotten fascia, a stained panel and a soaked floor two years later. If you can see a gap from the ground, it is already letting weather in.
If your roof is a corrugated cement type of the age that may contain asbestos, do not brush, drill, cut or pressure-wash it. Leave it alone and call us.
Asbestos cement is generally low risk while it is intact and left undisturbed; the risk comes from releasing fibres, and abrading, cutting or jet-washing the sheet does exactly that. Work with asbestos in the UK is governed by the Control of Asbestos Regulations 2012, with practical guidance in the HSE’s asbestos essentials task sheets, and the waste itself is hazardous waste with GOV.UK disposal rules attached to it. That is why “I’ll just give it a clean” is the one piece of garage maintenance we ask you not to do.
Start with our guide to spotting asbestos on UK garage roofs, and see understanding asbestos garage roof removal for how removal actually works. Our contractors are trained in asbestos awareness, Categories A and B; material is removed to a licensed disposal depot in accordance with Environment Agency and hazardous waste requirements, we recycle wherever possible, and full disposal paperwork is provided.
From 35 years in the trade: keep that disposal paperwork with your house papers. When you come to sell, the buyer’s solicitor asks about the garage roof, and a dated consignment note answers it in one line.
Roof trusses and steelwork are supplied primed. Primer is a protective base coat, not a finish coat, and it is not intended to be the building’s permanent weather protection.
Once the building is a few years old, exposed steel benefits from a coat of a suitable metal paint before any surface rust takes hold. The order matters: paint clean, sound primed steel and you are simply topping it up; wait until it is scaling and you are into wire-brushing, rust treatment and, in the worst cases, replacing spars and brackets. Spar shelving brackets, eyebolts, roofing bolts, clips and washers are all stocked in our spares shop if something is beyond painting.
Any exposed timber should be re-treated annually with a suitable preservative, particularly fascias and door frames. Those are the two places where timber sits closest to running water and takes the most weather.
Do it in dry weather on dry timber, and pay particular attention to end grain and to the top edge of a fascia, which is where water sits and where rot starts. New fascias fitted at the same time as a roof replacement are far cheaper than fascias fitted as their own job — see garage revamps.
Up-and-over and personnel doors are galvanised steel with a powder-coated primed finish. Keep the mechanism, springs and lock lightly lubricated, and keep the door running true.
A door that has started to bind will usually be a cheap fix now and an expensive one later. Binding puts load through the springs, wires and pulley wheels, and those parts fail in that order.
| Part | Twice-a-year attention | Warning sign |
|---|---|---|
| Springs | Light lubrication | Uneven lift, door rising crooked |
| Wires and cables | Visual check for fraying | Strands lifting, slack on one side |
| Pulley wheels and brackets | Light lubrication, check tightness | Grating, wheel not turning freely |
| Lock and handle | Light lubrication of barrel and cam | Key stiff, cam not throwing fully |
| Frame and running gear | Check the door closes square | Door binds or rubs on one side |
| Finish | Wash down, touch in chips | Rust spots on the powder-coated surface |
Doors, locks, cams, springs, cables, pulley wheel assemblies and brackets — including parts for obsolete Compton buildings that nobody makes any more — are stocked in our spares shop. If the door is beyond parts, a replacement steel up-and-over door is the single most common upgrade we fit.
If you are painting the floor or lining the walls, allow plenty of time for the concrete to dry first. Floor paint and linings applied over damp concrete fail — the paint lifts, and a lining traps moisture against the wall.
Use a dry heat source, such as an electric heater, rather than a gas heater, which puts moisture back into the air as it burns. That is the point most people get wrong: burning gas produces water vapour, so a bottled gas heater in a closed garage is adding to the problem you are trying to solve. It also produces combustion gases in an enclosed space — see the NHS guidance on carbon monoxide poisoning — so ventilation matters as much as the drying does.
Ventilate as well as heat: a closed, heated garage simply holds the moisture. Leave a door or window open enough to let damp air out.
Eaves and foam filler make a surprising difference. They close the profile of the sheet at the ridge and the eaves, which stops wind driving under the roof line and taking rain, leaves and birds with it.
It is far easier to fit as part of a roof replacement than afterwards, because the fitter is already at the sheet line with the sheets open. Retro-fitting means going back up to a finished roof and working blind along an edge. If you are having a roof replaced, confirm before the job that eaves filler is included; it is one of the details that quietly disappears from a cheap quote, along with fixing centres — see the true cost of cheap garage roofs and why sheet gauge matters. Big6, B5 profile and similar foam fillers are stocked.
| Item | Frequency | Do this |
|---|---|---|
| Gutter and outlet | Twice a year, and after autumn leaf fall | Clear debris, flush, check water leaves the downpipe |
| Ridge and eaves | Twice a year, from the ground | Sight along both lines for gaps, lifted flashing, loose fixings |
| Exposed steelwork | From a few years old, then as needed | Coat with a suitable metal paint before rust takes hold |
| Exposed timber | Annually | Re-treat with a suitable preservative, fascias and door frames first |
| Door mechanism, springs, lock | Twice a year | Light lubrication; make sure the door runs true |
| Floor and lining work | Before painting or lining | Dry the concrete with dry heat and ventilation, not gas |
| Suspected asbestos cement roof | Never disturb | Do not brush, drill, cut or pressure-wash — call us |
Nothing on that list needs a roof ladder, scaffolding or a specialist. If a job does, that is the point to ring us rather than to improvise. There is more background in our buyer’s guide to concrete sectional garages and workshops, what governs replacement roof lifespan and seven dangers in old garages.
If something needs putting right, send us a few photographs by WhatsApp, and we will tell you honestly whether it is a repair or a replacement. We would rather sell you a bag of clips than a roof you do not need.
We supply and fit; our contractors are time-served and approved, and the price we quote is the price you pay. If the answer is a new roof, what a re-roof day involves and why a new roof beats a new garage set out what happens next; if the building genuinely is beyond saving we will say so, and we cover garage removal and new garages too.
ComptonRoofs.com — Freephone 0800 318359, 10am to 4pm. WhatsApp photos to 07902 465165. Or use the contact page.
A few minutes twice a year is enough for most of it: gutters and outlet, a sight along the ridge and eaves from the ground, and light lubrication of the door gear. Exposed timber needs re-treating annually, and exposed steelwork needs a coat of suitable metal paint once the building is a few years old.
Standing water is the single most common cause of stained panels, rotten fascias and damp inside. Clear the leaves and moss and check the outlet is actually running — if water pools in the run, the supports or the outlet need attention rather than the gutter being emptied again.
Not if it is a corrugated cement roof of an age that may contain asbestos. Do not brush, drill, cut or pressure-wash it — leave it alone and call us. Work with asbestos is governed by the Control of Asbestos Regulations 2012, and abrading or jet-washing the sheet is what releases fibres from otherwise intact material.
Roof trusses and steelwork are supplied primed, and primer is a base coat rather than a finish. Once the building is a few years old, give exposed steel a coat of a suitable metal paint before any surface rust takes hold; that is far less work than treating scaled rust later.
Annually, with a suitable preservative, in dry weather on dry timber. Fascias and door frames sit closest to running water and take the most weather, and the top edge and end grain are where rot starts.
It is worth dealing with promptly. Keep the mechanism, springs and lock lightly lubricated and the door running true; a door that has started to bind will usually be a cheap fix now and an expensive one later, because binding loads the springs, cables and pulley wheels until they fail.
Allow plenty of time — paint and wall linings applied over damp concrete fail. Use a dry heat source such as an electric heater rather than a gas heater, which puts moisture back into the air as it burns, and ventilate while you heat so the damp air can leave.
It makes a surprising difference to draughts and to wind-driven rain, but it is far easier and cheaper to fit as part of a roof replacement than afterwards. If you are having a roof replaced, check that eaves filler is included in the quote.
Yes — keeping the building clear of standing water and maintaining exposed steel and timber is what keeps a structural guarantee intact. Routine care of that kind is expected of the owner under most building and roof-system guarantees, ours included.
Send us a few photographs by WhatsApp on 07902 465165 — each elevation, the roof line from the ground and the doors — with the building’s width and length. We will tell you honestly which it is. We supply and fit, our contractors are time-served and approved, and the price we quote is the price you pay.
Written by the Compton Roofs team — a family-owned and managed concrete garage specialist. Our owner has 35 years’ hands-on
Written by the Compton Roofs team — a family-owned and managed concrete garage specialist. Our owner has 35 years’ hands-on
