If the gutter is clear and still leaks or overflows, the fault is one of four things: a perished seal at a joint, sagging between brackets, a fall running the wrong way, or a downpipe that is restricted below the point you can see. Each is a cheap repair, and each does expensive damage if left.
- Clearing a gutter that is already clear fixes nothing. Watch it in heavy rain instead.
- Rubber seals in plastic gutter joints perish in roughly 10 to 15 years.
- Brackets at the wrong spacing let the gutter sag and hold water permanently.
- The damage a leaking gutter does to the wall costs many times the repair.
Clear, and still leaking
Blocked gutters are the well-known problem and clearing them is covered separately. This page is about the other situation: the gutter has been cleared, there is nothing in it, and it still leaks or spills over the front in heavy rain.
That is a fault in the gutter itself, and it is worth identifying rather than clearing again. There are four common causes and you can usually tell them apart from the ground in a heavy shower.
It drips steadily from one point between rain. A joint. The seal has perished or the bracket has pulled the joint open.
Water sits in a visible pool along the run. Sagging, or no fall. The gutter is holding water rather than moving it.
It spills over the front edge in heavy rain only. Either the capacity is inadequate for the roof area, or the outlet is restricted.
It overflows at the top of the downpipe, or the downpipe runs dry while the gutter is full. Restriction in the downpipe or at the shoe.
The single most useful diagnostic costs nothing: go outside during heavy rain with an umbrella and watch. Where it spills, whether the downpipe is running, and whether it is dripping or pouring tells you more in two minutes than an inspection on a dry day.
The four faults
| Fault | How it shows | Repair |
|---|---|---|
| Perished joint seal | Steady drip from one point, stains below | Replace the union seal or the union |
| Sagging between brackets | Standing water; visible dip | Add brackets; reset the line |
| Fall the wrong way | Water runs away from the outlet | Reset the brackets to a fall |
| Blocked or restricted downpipe | Overflow at the top of the pipe | Rod it; check the shoe and gully |
| Undersized for the roof | Spills only in heavy rain | Larger section, or a second outlet |
| Cracked gutter section | Drip not at a joint | Replace that length |
| Bracket pulled from rotten fascia | Gutter dropped at one point | Repair the fascia first |
| Gutter laid dead level | Silt and standing water along the run | Reset with a fall to the outlet |
Rows two, three and eight are all the same underlying problem: the gutter is not actually delivering water to the outlet. They are the most commonly missed, because on a dry day a gutter with no fall looks perfectly fine.
Joints and brackets
Why joints fail
Plastic guttering is joined with unions containing a rubber seal, and that seal is a consumable. It hardens and shrinks with UV and temperature cycling, typically over ten to fifteen years, and then the joint weeps. It is a small, cheap part. The usual mistake is to smear the leaking joint with silicone, which sticks to the dirt rather than the plastic, fails within a year, and makes the proper repair harder because the union now has to be cleaned before a new seal will seat. Replace the seal, or the whole union.
Thermal movement at the joint
Plastic gutter expands and contracts noticeably along its length. Unions have an expansion gap, and the gutter should be cut to leave it rather than butted hard. A run fitted tight on a cold day pushes the joints apart in summer; one fitted tight on a hot day opens gaps in winter. Several joints leaking along one run usually means the run was fitted with no allowance for movement.
Bracket spacing and fall
Brackets need to be close enough that the gutter cannot sag between them — roughly a metre apart, closer on exposed elevations or where snow loads. They also need to step down gradually so the whole run falls to the outlet. A gutter set dead level holds a film of water along its length, which collects silt, grows moss, and freezes. The usual cause of bad spacing or fall is a gutter that was replaced quickly by reusing the old bracket positions.
The fascia behind it
Brackets are only as sound as what they screw into. Where the fascia has softened, brackets pull out under the weight of a full gutter and the run drops at that point. That then holds water, which keeps the fascia wet. Refixing into a rotten fascia lasts a season. The fascia has to be dealt with first, which is often how a gutter repair turns into a roofline job.
Downpipes: the part nobody looks at
Downpipe problems are under-diagnosed because the pipe is vertical, the defects are usually at the bottom or inside, and everyone looks at the gutter.
Blockage at the shoe or the bend. Debris passes along the gutter, drops into the downpipe and lodges at the first bend or at the shoe at the bottom. The gutter then backs up and overflows, and clearing the gutter again achieves nothing. Rodding from the bottom usually clears it.
A cracked pipe behind a bracket. A hairline split lets water run down the wall behind the pipe, where you cannot see it. The sign is a damp stripe on the wall, or moss growing in a vertical line, with no visible drip. This causes a lot of internal damp that gets attributed to rising damp.
Discharging onto the ground. A downpipe ending in a shoe over open ground, rather than into a gully, delivers a roof's worth of water to the base of the wall every time it rains. Extremely common and trivially fixed.
A blocked gully. The downpipe is perfect and the gully below it is full of silt and leaves, so water backs up and spreads around the base of the wall. Clearing a gully takes minutes.
A disconnected or collapsed underground run. Where the gully takes water but it reappears nearby, or the ground stays wet, the underground drain may have failed.
Undersized for the catchment. One downpipe serving a long run or a large roof area will overflow at the top in heavy rain even when everything is clear.
Guttering lifespan, and when to replace rather than repair
Replacement becomes the better answer at the point where you are repairing the same run repeatedly.
uPVC guttering typically runs 20 to 25 years before it becomes brittle, discoloured and prone to cracking, though the joint seals will have needed attention well before that. Once a run has gone brittle, every repair cracks something adjacent.
Cast iron lasts very much longer where it is maintained — painted inside as well as out — and fails at the bolted joints and the back edge rather than generally. Repairing it is often viable and worth pricing against replacement.
Cast aluminium is long-lived and largely maintenance free.
The signal to replace rather than repair: more than two or three failing joints on one run, brittleness when handled, sagging that cannot be corrected because the fascia has gone, or a section that was always undersized for the roof.
The other trigger is access. Most of the cost of a small gutter repair is getting up there safely. Where scaffold or a tower is going up anyway — for roof work, fascias, or painting — that is the moment to deal with the guttering, because the access is already paid for.
What it costs
These are the roofline figures published across this site:
| Job | Typical Coventry guide price | Notes |
|---|---|---|
| Gutter clean & reseal | £80–£200 | Clears blockages, stops overflow |
| Per elevation (fascia + gutter) | £400–£700 | Front or rear |
| Full uPVC fascia, soffit & guttering (semi) | £1,000–£1,500 | Supply & fit |
| Labour | ~£30/hr | Qualified roofline fitter |
A single failing joint is an hour's work plus access. The reason small gutter repairs can seem expensive relative to the part is that access dominates, which is also the argument for dealing with the whole elevation at once rather than one joint at a time.
Then it is a fault rather than a blockage. We check the fall, the brackets, the joints and the downpipe rather than just clearing it again.
Frequently asked questions
Why does my gutter leak when it is not blocked?
Four common faults: a perished seal at a joint, sagging between brackets, a fall running the wrong way, or a restricted downpipe. Watching it during heavy rain tells you which — where it spills, whether it drips or pours, and whether the downpipe is actually running.
How long do gutter joint seals last?
Roughly ten to fifteen years. The rubber seal inside a union hardens and shrinks with UV and temperature cycling, then the joint weeps. It is a cheap part. Do not smear silicone over it — it sticks to the dirt, fails within a year and makes the proper repair harder.
How far apart should gutter brackets be?
Roughly a metre, and closer on exposed elevations. They also need to step down gradually so the run falls to the outlet. A gutter set dead level holds water along its length, collects silt and freezes. Bad spacing usually comes from reusing the old bracket positions during a replacement.
Why does my gutter overflow at the downpipe?
Something is restricting the downpipe — most often debris lodged at the first bend or at the shoe. Clearing the gutter again will not help; the pipe needs rodding, usually from the bottom. Check the gully beneath it too, since a silted gully backs water up just as effectively.
What causes a damp stripe on a wall with no visible leak?
Often a hairline crack in a downpipe behind a bracket, letting water run down the wall out of sight. The giveaway is a vertical damp line or moss growing in a stripe. It causes a lot of internal damp that gets wrongly attributed to rising damp.
What is the lifespan of guttering?
uPVC typically runs 20 to 25 years before it becomes brittle and prone to cracking, though the joint seals need attention well before that. Cast iron lasts very much longer where it is painted inside as well as out, and cast aluminium is long-lived and largely maintenance free.
When should guttering be replaced rather than repaired?
When more than two or three joints on a run are failing, when the plastic has gone brittle so each repair cracks something adjacent, when sagging cannot be corrected because the fascia has rotted, or when the section was always undersized for the roof area.
Watch it in the rain
We diagnose on a wet day where we can, because a gutter with no fall looks perfectly fine when it is dry.