Can commercial gutters be repaired?
Usually, yes. On factories, warehouses and other large buildings, most gutter leaks start at the joints, the outlets or a patch of corrosion, not because the whole gutter has failed. If the gutter itself is still structurally sound, those faults can be repaired and the whole run lined or coated so it’s watertight again, without taking it out.
That applies to most types of commercial gutter: steel box gutters and valley gutters on industrial roofs, older cast iron gutters, and concrete gutters. Replacement is only needed when the gutter can’t be saved, and it is usually the most disruptive option.
What goes wrong with commercial gutters?
Industrial roofs collect a lot of rainwater. Box gutters are usually laid level, so water sits in them between the outlets even when it isn’t raining, and leaves, silt and debris hold it against the metal (Roofing Today). The most common faults are:
- Failed joints: gutter sections are bolted together with a flexible seal. As the building moves, the seal breaks down and the joint starts to leak.
- Corrosion: steel gutters rust where wet debris sits, eventually leading to pinholes and then larger holes.
- Blocked outlets: water backs up and overflows into the building, or over the edge.
- Cracked joints in concrete gutters: sections move with the weather, and water gets through the joints.
- Old repairs: bitumen, mastic or felt patches that have failed can trap water against the gutter and hide corrosion underneath.
Your options: repair, lining or replacement
Patch and joint repairs
Sealing a leaking joint or patching a hole fixes a single problem. It suits a gutter that is otherwise in good condition. Where corrosion or joint failure runs along the whole gutter, patch repairs tend to be short-lived, because the next joint along is usually close behind.
Liquid coatings
A liquid coating is brushed, rolled or sprayed onto the cleaned gutter and cures into a seamless waterproof layer. Coatings cope well with awkward details such as outlets, corners and stop ends. But a coating is only as good as the surface it bonds to: the gutter needs to be structurally sound, free of corrosion, clean and completely dry, and old repairs need to come off first. Because it’s bonded to the gutter, a coating over the old joints also has to cope with the same movement that broke the original seals (Roofing Today).
Membrane and rubber linings
A rubber or other membrane lining is fitted inside the existing gutter, either bonded to it or laid loose. The old gutter then acts as a carrier, so it needs to be sound, but the lining does the waterproofing. A loose-laid lining isn’t stuck to the gutter, so it copes with uneven gutters and isn’t pulled about by movement at the old joints.
Rigid, factory-made liners (a steel tray with a rubber or PVC membrane bonded to it) can go into gutters that have lost some of their strength. They have to be smaller than the gutter they sit in, though, which reduces how much water it can carry (Roofing Today).
GRP linings
GRP (glass-reinforced plastic) comes as a ready-made liner that sits inside the gutter, or as a liquid product laid up in place. Like other linings, it needs a sound gutter underneath.
Replacement
A gutter needs replacing when it is rusted through along its length, distorted or sagging, or its supports have failed. Replacement is also worth considering if the gutter is too small for the roof and overflows in heavy rain, or if the roof is being reclad anyway. It costs more and usually means more access equipment, more work at the roof edge and sometimes lifting roof sheets.
| Option | Best for | Check first |
|---|---|---|
| Patch and joint repairs | One or two leaks on a gutter in good condition | Whether other joints are about to fail |
| Liquid coating | Sound gutters with awkward shapes or many outlets | The gutter can be made clean, dry and free of rust |
| Membrane or rubber lining | Long runs of box or valley gutter, uneven gutters | The gutter is strong enough to carry the lining |
| Rigid liner | Gutters that have lost some strength | Whether the smaller gutter can still carry the water |
| GRP lining | Sound gutters that need a hard-wearing finish | The same as other linings |
| Replacement | Gutters rusted through, distorted or too small | Access, roof sheets and the disruption inside |
How do you choose?
Start with a survey, after the gutters have been cleaned out. Corrosion and split joints can’t be judged under a layer of silt. A good survey checks:
- the condition of the metal or concrete along the whole run, not just where it leaks;
- the joints, outlets and any old repairs;
- the supports and brackets;
- whether the gutter overflows in heavy rain. A lining takes up some of the gutter’s depth, so gutters that are already too small need to be checked before lining.
At Locus Services, a gutter repair and lining survey ends with a report recommending repair, lining or replacement. We can show you samples of the rubber and membrane linings we use, so you can see what you’re paying for.
How long does a gutter lining last?
It depends on the system, how well the gutter was prepared and how well it’s maintained afterwards. Manufacturers’ guarantees vary. For example, one liquid gutter coating listed on the NBS specification library carries a 15-year guarantee (NBS), and one rigid rubber (EPDM) lining system carries 30 years when fitted by an approved contractor (NBS).
Before you choose, ask what the guarantee covers (materials, workmanship or both) and what maintenance it needs. Whatever you choose, keep the gutters clear: debris left sitting in a lined gutter still blocks outlets and causes overflows. Locus recommends cleaning commercial gutters at least twice a year.
Working safely on commercial roofs
Gutter work on industrial buildings means working at height, often next to fragile roof sheets and rooflights. HSE says almost one in five deaths in construction work involve roof work, many of them people repairing and cleaning roofs, and that all roofs should be treated as fragile until a competent person has confirmed they are not (HSE).
Older gutters can also contain asbestos. HSE lists asbestos cement gutters and downpipes among the places asbestos is found, in any building built or refurbished before 2000 (HSE). Check your asbestos register before any gutter work starts.
Our operatives are trained to work at height and on roofs. After the survey, we write a safe working plan covering how we’ll get onto your roof and work on it.
