Most conservatory roof leaks come from one of seven places: blocked gutters, the join with the house wall, perished gaskets on the roof bars, cracked sheets, open polycarbonate flutes, slipped sheets or failed glass seals. A single leak on a roof under 10 years old is usually worth repairing. Leaks in several places on a roof over 15 years old usually are not.
First, check it is actually a leak
A lot of water inside a conservatory is condensation, not rain. Polycarbonate and older glass are cold on the inside surface, so moisture from the room condenses on them and runs down the roof bars. It then drips from the lowest point, which looks exactly like a leak.
The test is simple. If water appears on a cold, dry morning after a clear night, it is condensation. If it only appears during or just after rain, and especially in wind driven rain, it is a leak. Some roofs have both. Our guide to conservatory roof condensation covers the first problem in detail.
How to trace where the water gets in
Water rarely drips where it enters. It runs along the underside of a bar or the top of a ring beam and falls at the lowest point, sometimes a metre or more away. These steps narrow it down without going on the roof.
- Mark the drip point with a piece of masking tape inside, and note the weather when it happened.
- Look upwards along the nearest roof bar towards the ridge and the house wall. Stains, dirt lines or dried water marks show the path.
- Check the gutters from the ground on a rainy day. Water spilling over the front edge means a blockage or a sag.
- Look at the join with the house wall. Cracked sealant, a gap under the flashing or damp patches on the house wall inside all point here.
- Run a garden hose gently over one section of the roof at a time from a stepladder at the gutter, with someone watching inside. Start low and work upwards so you know which section set it off.
Never climb onto a conservatory roof or lean a ladder against the roof bars or gutter. Neither is designed to take a person's weight, and polycarbonate and older glass can give way without warning.
The seven usual causes
| Cause | Signs | Can it be repaired? |
|---|---|---|
| Blocked or sagging gutter | Water over the front edge, drips along the frame head | Yes, clear and refix; gutters are cheap to replace |
| Join with the house wall | Leaks at the back of the room, damp on the house wall | Usually, by resealing or renewing the flashing |
| Perished bar gaskets | Drips along the length of a roof bar, often in several places | For one bar yes; if they have all aged, it rarely lasts |
| Cracked polycarbonate sheet | Visible crack, water in the flutes | Yes, swap the sheet |
| Open or failed flute ends | Green or black growth in the channels, water at the eaves | Sometimes, by retaping; dirty flutes often cannot be cleaned |
| Slipped sheets | Gap at the ridge, sheet overhanging the gutter | Yes, push back and fix; tends to recur on older roofs |
| Failed glass unit seals | Misting between panes, leaks round the unit edge | Yes, replace the unit |
When a repair is the right call
A repair makes sense when the problem is in one place and the rest of the roof is in good order. A roof under 10 years old with a single leak at a gutter or wall join is the classic case. Clearing a gutter, resealing a flashing or replacing one sheet can buy many more years.
Repairs also make sense if you are happy with the room as it is. If you use the conservatory comfortably through the year and the only complaint is water, fix the water and keep your money.
When replacing the roof makes more sense
Replacement becomes the better option once repairs start chasing the problem around the roof. Signs of this include leaks in more than one place, leaks that return within a year of a repair, yellow or brittle polycarbonate and several misted glass units. Seals and gaskets tend to age together, so fixing one often moves the water to the next weakest joint.
It also makes sense if the room is too cold in winter and too hot in summer anyway. If you are going to spend money on the roof, it is worth asking whether the same money could fix the leak and the comfort problem together. Our guide to the signs your conservatory roof needs replacing has a quick checklist.
The costs side by side
Repair costs depend on the job and access, so get a written price for any repair. For a full new roof, these are typical figures for a small conservatory.
| Option | Typical price | Roof U-value | What stays the same |
|---|---|---|---|
| New polycarbonate sheets (3 m by 3 m) | £2,000 to £3,500 | 1.6 for 25 mm, 1.4 for 35 mm | Heat in summer, cold in winter, rain noise |
| New glass roof (3 m by 3 m) | £3,300 to £5,200 | 1.0 to 1.2 for modern low-e | Direct summer sun |
| Internal insulation under the old roof | £1,000 to £3,200 | Varies by system | The old roof and its leaks stay on top |
| Insulated aluminium panels (up to 12 m²) | From £3,000 | About 0.43 | Your existing frame |
Internal insulation deserves a special mention. It is fitted under the existing roof, so it does nothing to stop a leak. Water that gets in above it can soak the insulation and stain the ceiling, and you will not see where it is coming from. Fix or replace a leaking roof before insulating under it.
Our panel price includes taking off and recycling the old roof, panels made to measure in your colour, fitting and a 10 year insurance backed guarantee. The full breakdown by size and style is on our conservatory roof panels cost page.
What happens to a leak when we replace the roof
When we fit panels, the old sheets or glass and their worn gaskets come off. The panels are made to measure and fitted into the existing roof bars with new seals, and we check the gutters and the join with the house wall at the same time. If the gutters and fascia need replacing, new gutters and fascia are £295.
A small lean-to or Edwardian usually takes one day, medium roofs one to two days and large or P-shaped roofs two to three days. Most single storey roofs need no scaffold. If rain is forecast on the day, we plan the work so the room is covered at the end of each day.
A temporary fix while you decide
If water is coming in now, clear the gutters and check the downpipe is not blocked, as that solves more leaks than anything else. Move furniture and rugs away from the drip point and put down a tray. Avoid filling joints with sealant from a tube on top of the roof, because it can trap water and make a proper repair harder later.
Next steps
If the leak is one of several problems with the roof, get a price range with the conservatory roof cost calculator and then book a free survey. We will find where the water is getting in and tell you straight if a repair would do.
Questions people ask
Why does my conservatory roof only leak in heavy rain?
Heavy or wind driven rain overwhelms gutters and pushes water past worn gaskets and flashings that cope with light rain. Check the gutters and the join with the house wall first.
Can I fix a leaking conservatory roof myself?
You can clear gutters and downpipes safely from a ladder against the house wall. Anything that means going onto the roof should be left to someone with the right access equipment.
Does home insurance cover a leaking conservatory roof?
Most policies cover sudden damage, such as a storm, but not wear and tear like perished seals. Check your policy wording and tell your insurer before making a claim.
Will insulated panels stop my roof leaking?
Yes, because the old sheets and worn gaskets come off and panels go in with new seals. We also check the gutters and the join with the house wall, which are common leak points.
