Question answered
Conservatory gutters: replacement and leaks
The short answer
Conservatory gutters leak at their joints, outlets and brackets, and overflow when leaves or moss block them or the fall to the outlet is wrong. Box gutters, the hidden channels where a roof meets a wall, and abutment flashings cause leaks that look like roof faults. Clean and re-seal first. Replace the gutter when it has split, sagged or lost its fall, and fit new ones whenever the roof is renewed.
A conservatory gutter drains a whole roof through a small channel. When it leaks or overflows, the water often looks like a roof leak from the inside.
Why a small gutter has a big job
Most conservatory gutters are plastic, in a narrow half-round or square section, fixed to the eaves beam or a fascia board. The roof above them is a single smooth surface, so every drop that lands on it arrives at the gutter within a minute or two. In a downpour, a short run with one downpipe can be overwhelmed.
That is why a gutter that copes with the house can still fail on the conservatory. It also explains why debris matters so much: a handful of leaves or a ball of moss at the outlet is enough to send the water over the front edge and down the face of the glazing frame.
Look for staining below the joints, green marks below the brackets and water stains on the cills. All of them point to a gutter that has been overflowing for some time.
A downpipe that discharges onto a flat paving slab can also splash back and soak the base of the frame, so check where the water goes after it leaves the gutter.
Joints, falls and brackets
Plastic gutters are joined with rubber-sealed unions that clip together. Those seals dry out and shrink with age, and the union then drips. Re-seating or replacing the seal is a quick job when the gutter is otherwise sound.
Water only moves along a gutter if the channel slopes slightly towards the outlet. Manufacturers commonly suggest a fall of roughly 1:600 to 1:350, varying with the system, and Brett Martin says to space supports at 900mm or less. When brackets loosen or the gutter sags between them, puddles stand in the low spot, collect silt and eventually split the plastic in a frost.
On a conservatory the eaves beam can move slightly with the seasons, so a gutter that was right when it was fitted can drift out of line. We use a spirit level on the run and not our eyes. The fix may be re-fixing the brackets, not replacing the whole run.
If a gutter has dropped at one end, it may be reset with new brackets and a fresh union seal in one visit.
Box gutters and the hidden channel at the wall
A box gutter is a rectangular channel, lined with lead or another waterproof sheet, laid between two roof surfaces or behind a low wall. On a lean-to conservatory, one often runs where the glazing meets the house, and it carries water from the house roof as well.
These gutters fail slowly. Lining laps open, debris builds up and a blocked outlet makes them overflow into the wall. The staining then appears on the inside of the conservatory ceiling or on the house wall, and the glazing gets the blame it does not deserve.
A box gutter needs its own outlet, a suitable fall and a lining that is dressed properly, with no shortcuts. If it is lined with felt and bitumen, or with sealant that has cracked, we advise relining it. Our page on leaking polycarbonate conservatory roofs covers the glazing-side joints that are easily confused with it.
Because the channel is hidden from the ground, the first sign is usually a stain, not a drip.
Abutments, flashings and the roof edge
The abutment is where the conservatory roof meets the house wall. It is sealed with a flashing, normally lead, tucked into the brickwork. If the flashing has lifted or its pointing has failed, water runs behind it and down the back of the gutter, giving the impression that the gutter itself leaks.
At the front of the roof, the last bar and the gutter must be arranged so that water leaving the roof lands in the channel and does not run behind it. Where the roof overhangs the gutter by too little, water drips past it. Where it overhangs by too much, wind can lift it.
Gutters also affect noise. A shallow plastic gutter under hard rain drums, which you can read about in why a conservatory roof is noisy in the rain.
On a lean-to the wall flashing and the top end of the gutter should be inspected together, since each depends on the other being sound.
Repair, replace, or renew with the roof
For a sound gutter with a dry seal, cleaning, re-sealing and re-fixing is enough. For one that has split, warped or lost its fall, replacement is better. MyBuilder (updated 21 August 2026) gives a typical UK range of £30 to £70 per metre for replacing guttering, and most conservatory runs are short. The price for your own roof is one total figure in the written quote after we have surveyed it.
If the roof is being replaced, the gutter should be too. A new roof changes the fall of the eaves and the position of the drip line, and it is wasteful to put old gutters under it. When a solid roof goes on, the gutter size is worth reviewing, since the tiled covering sheds water differently. See how long a solid conservatory roof takes for how the stages fit.
Our conservatory roof replacement page lists the full options.
If you collect several prices, find out which of them cover VAT and scaffolding.
Conservatory gutter faults: two more questions
Can I clear a conservatory gutter myself?
Only from a safe, stable position, and never by standing on the conservatory roof, which can crack. Use a proper ladder footing on the ground, wear gloves and keep three points of contact. If you cannot reach it safely, ask for a visit.
Why does water run behind my conservatory gutter?
Usually the roof edge and the gutter are out of step. The gutter may sit too low or too far out, so water leaves the last bar and misses the channel, or the fall has been lost so it overflows at the back. We check the line with a level.
Tell us about your roof
Describe what is happening and we will call you back to arrange a visit.
- Photographs of what we find
- A written quote with one total price
- Or call 01903 299063
10-year workmanship guarantee, in writing.