The short answer
Yes, in most cases a garage should have guttering, because a roof with no gutter dumps every drop against the walls and the door. A gutter needs a gentle fall to its outlet, firm brackets and a downpipe that ends in a proper drain or soakaway. MyBuilder's guide, updated 21 August 2026, gives £30 to £70 per metre for replacement guttering.
Why a garage gutter matters more than it looks
A garage roof is small, but it still sheds a surprising volume of water in one heavy shower. With no gutter, that water leaves the edge in a sheet and lands on the strip of ground beside the wall. Over a few winters it splashes mud and grit up the masonry, keeps the lower courses of brick or block permanently damp, and runs under the up-and-over door or the side door sill.
Flat garage roofs are the worst affected. The covering usually finishes at a drip edge, and the water falling from it hits the same few inches of ground every time. Pitched garage roofs spread the load along the eaves, but the effect is the same: wet walls, green staining and a path that never dries.
A gutter does not make a leaking roof watertight, and it will not cure a failing felt. What it does is take clean, controlled water away from the building. If the roof itself is the worry, our page on why garage roofs leak deals with that side of the problem.
Fitting a gutter to a flat or a pitched garage roof
On a pitched garage, the gutter hangs from brackets fixed to the fascia, the board that runs along the foot of the rafters. That is a simple job when the fascia is sound. Where a garage has bare rafter ends, as many older ones do, the gutter is carried on brackets screwed straight into the timber, and the rafter ends are worth checking for rot first.
A flat roof is different. There is often no fascia at all, only a thin timber trim or a metal drip. The roofer may fit a deeper board to give the brackets something to bite into, or use a gutter designed to clip under the edge of the covering. Either way, the roof edge detail and the gutter should be planned together, so the covering overhangs the gutter by a few millimetres and drains into it rather than behind it.
Sheet roofs bring another point. Corrugated cement and profiled steel sheets throw water off at the eaves with some force, and the gutter has to sit under the lowest corrugation. If the garage is a cement-sheet one, read our note on how asbestos cement is removed before anyone drills or cuts near it.
Fall, brackets and the downpipe
Gutters must run slightly downhill towards the outlet, otherwise water stands in the channel, grows moss and overflows at the joints. Makers of gutter systems usually ask for a slight slope towards the outlet, somewhere between 1:600 and 1:350 depending on the product. On a short garage run that is only a few millimetres across the whole length, which is why a gutter fixed by eye often ends up flat or backwards.
Support matters as much as slope. Brett Martin suggests brackets no more than 900mm apart, closer in areas of heavy snow, while FloPlast's small-bore guide gives 500mm as the maximum on straight runs. Always follow the data sheet for the system actually being fitted. Where a run droops between its brackets, a pond forms in the channel, and in frost the ice can split a joint.
The downpipe is the last part. It should finish over a gully, a drain or a soakaway, not on the path. A garage that sits beside the house may be able to join the house drainage, which is a decision for your roofer and the drainage layout, not a guess. A short rainwater diverter into a water butt is a sensible option too, provided the butt has an overflow that goes somewhere safe.
What replacing garage guttering costs
National guides give a useful starting point. MyBuilder's gutter, fascia and soffit guide, updated 21 August 2026, puts replacement guttering at £30 to £70 per metre. A single garage often has one or two short runs, so the total is modest, but the same guide says access can change the picture. Where a garage is low and reachable from a ladder, there is little to add. Where it sits behind an extension or in a tight rear yard, getting at it takes more effort.
The price of the system itself depends on the profile and material. Half-round and square plastic are the usual choices, with cast-style or aluminium for garages that match an older house. Replacing a fascia board at the same time, which is sensible when it is rotten, adds to the figure, and so does clearing away the old gutter.
These are typical UK figures, not a price for your garage. Our written quote follows the survey; if you collect other prices, find out whether each one includes VAT. If you are already having the garage re-covered, ask for the gutter to be priced in the same visit so access is shared.
Cement-sheet garages and other cases to treat with care
Some older garages have gutters made from asbestos cement, as well as roof sheets. HSE treats careful, unbroken removal of asbestos cement roof sheeting and rainwater goods as non-licensed work. It is still a task for people trained to handle the material, not for a stepladder and a lump hammer. If you suspect your gutter or sheets are old cement, our page on fitting rooflights into sheet roofs explains why cutting into them is a bad idea, and our survey will tell you what you have.
Sheds and small outbuildings are a separate case again. A shed with a felt covering can take a small plastic gutter and a butt, and our guide to felt shingles on sheds covers the roof itself. Open structures such as carports usually need a gutter on the lower edge only, and the carport roof page explains the options.
If your garage needs more than a new gutter, see our garage roof replacement overview. If a new gutter is all the garage needs, that is what we will put in writing, alongside survey photographs from your own roof.