A conservatory roof that drips onto the sofa rarely needs to be replaced the same week. In many cases the leak has a specific, fixable cause: a perished seal along a glazing bar, a cap that has lifted, a cracked pane, a tired flashing against the house wall, or a gutter that has backed up under the edge of the roof. Finding which one is the skill, because water travels along bars and behind cappings before it appears, often a long way from where it got in. This guide describes how those faults are traced and repaired, what the work involves on glass, polycarbonate and aluminium or uPVC bars, and which signs show a roof can no longer be mended economically. It will help you judge a repair quote and ask better questions of whoever comes to look. Where the roof is sound but cold or hot, repair is the wrong tool, and the pages on insulation and conversion are better places to start.
Where conservatory roofs actually leak
A conservatory roof is a set of panels held in a grid of bars and sealed at every edge. Water has to be stopped at four types of joint, and every one ages differently.
The first is the joint between the panel and the bar. Glass units and polycarbonate sheets sit on a rubber or foam gasket and are held down by a cap screwed through the bar. As the gasket ages it hardens and shrinks, and a gap opens along the side of the panel. The second is the cap itself. Caps can lift in wind, and the screws and end seals are small targets for water. The third is the ridge and the eaves. At the ridge, the panels meet a capping piece, and at the eaves they finish on a cill or a gutter. Both have end closures and seals that fail with age. The fourth is the junction with the house, where the roof meets a brick wall and is closed with a lead flashing or a proprietary seal.
Gutters are the quiet cause. A blocked or sagging gutter at the eaves can let water run back under the lowest panels. What looks like a failed seal may be the gutter overflowing across it.
Condensation mimics a leak without being one, and many calls about drips turn out to be moisture running down the cold underside of the glazing. A small bead of water appearing on a still, damp morning is condensation, whereas a patch that spreads after a downpour is a true leak. The first job is always to find out which of the two you have, and the season matters for any work that follows, as our answer on replacing a conservatory roof in winter explains.
How a leak is traced
Tracing takes patience, and that patience is what divides sound repairs from guesses. The method is the same whatever the roof is made of.
It begins inside, with a note of exactly where and when the water appears, and whether it comes only in driving rain or after any rain at all. Staining on a bar, a rusty screw or green algae along a seam show the route. From outside, the roof is checked for lifted caps, missing screw covers, cracked or crazed panels, slipped end closures and gaps along the house wall.
Where the cause is not obvious, the roof is tested in sections with a hose, starting at the lowest point and working up the slope. The person inside calls out when the first drop appears, so the entry point is narrowed to one panel or one bar. Spraying the whole roof at once tells you nothing, because everything leaks at once. Working from the bottom up avoids the false trail that comes from water running down and sideways before it shows.
This is one reason a quick, cheap fix on the nearest drip so often fails. A sealant smeared on the visible gap treats the exit, not the entry. The leak returns next month a foot away. A roofer who tests properly will usually be able to tell you what part has failed, and whether the repair is a ten-minute reseal or a replacement of a whole run of gaskets.
Access matters too. A conservatory roof is fragile in places. Polycarbonate sheet can crack under a person's weight, and old glass can break, so work is done from crawling boards or from a ladder set against the frame, not by walking on the panels.
Bars, caps and gaskets
The bars are the spine of the roof, and most repairs relate to them or to the seals they carry.
Resealing
A perished gasket can sometimes be improved by lifting the cap, cleaning the bar and panel edge, and applying a suitable sealant before the cap goes back. That is a patch, and it can last for a season or for several years depending on the condition of the rubber. If the gasket has hardened, shrunk or split along a run, sealing over it is a short-term measure and the better repair is new gasket along the whole bar.
Replacing gaskets and caps
Replacing gaskets means lifting each panel along the bar, removing the old rubber, fitting new and bedding the panel back. It is time-consuming, because one bar serves two panels and each panel sits on four edges. A full re-gasketing of a roof is a day or more of careful work, and it is sensible only when the bars and panels are in good condition.
Bars themselves
Aluminium bars corrode slowly, and white powder or pitting at the fixing points shows it. uPVC bars with internal steel can rust from within if water gets in at a cut end. Where the bar itself is damaged, replacing it means taking out the panels on both sides, which approaches the cost of a new roof. It is worth knowing this early, because a quote that treats the bars as fine is only fair if they are.
Fixings
Loose or missing screws and screw covers are a simple and common fault. A cap that has lifted may need new screws, a new cover strip and a reseal at the end, which takes minutes once the cause is understood.
Panels: polycarbonate, glass and failed units
Panels fail in different ways depending on what they are made of.
Polycarbonate sheet can crack from impact or brittleness, yellow or cloud over time, and let water into its internal channels if the end seals fail. The tape and vent strips on the ends are easy to overlook. If the top end is open, dust and insects get in, and if the bottom end is sealed with the wrong tape, water collects inside and shows as green or grey streaks. Typical UK sources give polycarbonate a life of about 10 years (HomeBuilding, 2024) or 10 to 15 years (The Eco Experts, 2024), so a roof past that age is likely to need more than a quick repair. A single cracked sheet can be replaced if the same thickness and profile are available, and our answer on whether you can replace just the polycarbonate sheets goes into the limits of that.
Glass units are different. A sealed double-glazed unit has a spacer bar and a perimeter seal, and when the seal fails, moisture gets between the panes and leaves a misty, fogged look that cannot be wiped off. The unit still keeps rain out, but it insulates less and looks poor. The usual remedy is to replace the unit with one cut to the same size, which is a repair, and which the same frame accepts. Cracked glass needs urgent attention, because it can drop shards, and the first step is to make the area safe by closing off the room below.
Matching is the practical difficulty. A new panel has to match the thickness, the spacer and the coating of its neighbours, or the roof looks patchy and performs unevenly. We cover the difference between simple repair and rebuilding the whole covering when we survey.
Flashings, ridge and gutters at the edges
Plenty of conservatory leaks begin at the edges, not out on the panels, and edge faults tend to be cheaper to cure.
The wall junction
Where the roof meets the house, a flashing is the strip of lead, or sometimes a flexible seal, that keeps rain from tracking down the brickwork behind the glazing. Its upper edge is fitted into a raked-out mortar joint or a cut groove, then sealed. Over time the sealant dries, the lead lifts or cracks, and the pointing above it crumbles. Re-dressing the lead and repointing the joint often cures a leak that appeared to come from the roof.
The ridge and eaves
The ridge cap and the end closures at the eaves hold the panels in place at either end. Their seals shrink and their fixings loosen. They can usually be refitted or replaced without disturbing the whole roof.
Gutters and downpipes
A conservatory gutter is small, and leaves, moss and roof debris fill it quickly. A blocked gutter overflows onto the frame and runs back inside, so clearing it and checking the fall is part of any repair. A sagging or cracked gutter needs resetting or replacing. Leaving it is a common reason a repair does not last.
Neighbouring roofs
A conservatory often sits below a main roof or a dormer, and water from above can land on it. If the leak follows rain on the house roof, the cause may be a gutter or valley above, not the conservatory at all, and the repair belongs there.
Repair, re-gasket or replace: making the call
The honest test is how much of the roof has failed, and how often. One leak, in a roof that is otherwise sound, is a repair job. Leaks in several places, a roof resealed more than once, panels that have yellowed or fogged, and bars with visible corrosion all point to a covering that is wearing out.
Cost helps frame it. MyBuilder's roof repair guide (2026) gives typical UK figures for general roof repairs: a minor job like one small leak at £100 to £300, a moderate repair at £500 to £1,000, and major work at £2,500 or more. Conservatory repairs sit within the same bands, though access and the need to match panels can push a job upward. The same publisher puts a full conservatory roof replacement at £2,000 to £10,000 or more, averaging about £4,500. These come from a national guide and say nothing about our own rates; the fixed figure arrives after the survey.
If repeated repairs would add up to a large part of a new roof, replacement is the better use of money. Comfort is a separate matter from leaks. A roof repaired and left as it is will stay cold in winter and hot in summer, so if comfort is the real complaint, a repair solves only half of it. Our page on using a conservatory all year explains what a change of purpose involves, and a look at orangery roofs with a glazed lantern shows one route for a conservatory that is being upgraded rather than patched.
We survey the roof from outside and inside, and photograph your own conservatory so the findings are shown to you. If repair is the right answer we say that, and price it as a fixed figure in writing. Where a new roof makes more sense we explain why, as part of our conservatory roof replacement service. Workmanship on the work we carry out is covered by our 10-year written guarantee.