How long does a garage roof last?

Published guides disagree a little, which is normal, because a roof's life depends on workmanship and upkeep as much as on the material. The table gives typical ranges from published cost and product guides, each with its date.

Less also observes that well-laid felt can reach 20 years whereas a bad job may give out inside 10. That gap sums up the subject: the product on the roll is only part of the story, and the person laying it, the deck beneath it and the care it gets afterwards decide where in the range your roof lands. Treat every figure here as a typical range, never a promise.

Garage roofs are often overlooked. Nobody goes up there, the gutter silts up, and a branch rubs the surface every windy night. A few causes turn up again and again when we survey.

Ponding is the first. Water has to be able to leave a flat roof, and BS 6229, as IKO summarises it, suggests designing for 1:40 so the roof as built ends up with 1:80 as a minimum. A deck that sags or was laid too flat holds puddles, and a puddle works on the covering all year.

Poor detailing at the edges and upstands is the second. Most leaks start at the junction with the house wall, around a pipe or at a drip edge, more than across the flat expanse. The third is a covering stuck over a damp deck, which blisters and splits from below. Finally, there is simple neglect: leaves, moss and silt left to rot on the surface, and foot traffic from someone clearing the gutter.

Pitched garages with tile or sheet roofs fail more slowly, but the same story applies to the fixings, the laps and the timbers beneath them.

Plenty of garages put up during the later twentieth century carry corrugated cement sheets. Age alone does not condemn them, but they do weather, grow moss, become brittle and crack when stepped on. HSE advice for pre-2000 buildings, built or refurbished, is to presume asbestos until shown otherwise, so our page on asbestos test costs matters if you are unsure what is overhead.

A cement roof does not have a tidy lifespan to match the table, because exposure, moss, past cleaning and foot traffic all change how it ages. A sheet that is flaking, sagging or showing daylight at the laps needs attention whatever its birthday, and a sound one may serve for years yet if nobody disturbs it. Taking such a roof off and getting rid of it follows its own procedure, laid out in our guide to the asbestos removal process.

Profiled steel sheets sit in the middle: long-lived when coated well and fixed properly, vulnerable at cut edges and laps where rust starts. A corroded sheet roof can look fine from the road and be tired underneath.

Early warnings show without anyone going on the roof. Look from an upstairs window or the garden, then check inside the garage with a torch.

• Brown stains or drips on the ceiling, particularly after a dry spell, which suggests a slow track of water.
• Blisters, ridges or open laps in felt, and a surface that has cracked into a crazed pattern.
• Puddles that linger on the surface for days after the rain has stopped.
• Sheets that move underfoot, or fixings that have worked loose.
• Moss and daylight along the ridge or at the eaves.

One patch is not a verdict. Patching makes sense while the remaining covering is in good order, and our page on repairing a felt garage roof shows what a good patch looks like. When the same roof needs a second or third repair within a short time, the roofer will usually recommend replacement, because patching a tired covering just moves the leak.

The longest-lived garage roofs are the ones fitted on a dry, sound deck with proper falls, clean details and a gutter that works. Our comparison of felt and EPDM garage roofs sets out how each behaves, and our notes on garage roof insurance explain why a roof that has simply aged is rarely something a policy will pay to replace.

Before you commit, ask three things. What material forms the deck, and is it dry? What falls will the finished roof have? And what is being done at the edges and wall junctions, where most failures begin?

Manufacturer warranties are not lifespans. A product may carry a long warranty and still fail early because of the installation. Our workmanship guarantee is for 10 years and is in writing, but it is not insurance-backed and does not stretch to wear and tear. If you want to know where your garage roof stands, our garage roof replacement page explains the survey. You receive pictures taken on your garage and a quote in writing, with advice scaled to the fault, whether that means a patch, a re-cover or leaving it alone for now. Garage roofs rarely call for urgency unless they are letting water in, so you have time to choose well.