If your roof lantern is leaking in heavy rain, deal with it from inside. Move furniture and electricals clear, put down a bucket and towels, and if water is pooling on the ceiling, pierce a small hole at the lowest point to let it drain in a controlled stream rather than bringing the ceiling down. Do not go onto the roof, and do not apply sealant in the wet. Photograph where the water is entering, then book a survey once the rain eases. A lantern that leaks in heavy rain has a kerb or flashing failure that only shows under load, and it needs replacing, not patching.
That is the immediate answer. The steps below expand it, and explain why climbing up and sealing it yourself makes the eventual job worse. This sits under our main roof lantern installation page.
Do this now, from inside
- Protect the room. Move furniture, rugs and anything electrical out from under the leak. Water tracking down a reveal can reach sockets and light fittings, so if it is near either, turn that circuit off at the consumer unit.
- Catch the water. Bucket under the drip, towels around it, a plastic sheet over anything that cannot move. Empty the bucket before it overflows.
- Relieve a bulging ceiling. If water is collecting in the plasterboard and the ceiling is sagging, put a small hole at the lowest point of the bulge with a screwdriver and let it drain into a bucket. A controlled stream is far better than a whole section of ceiling coming down at once.
- Note the timing. Whether it leaks only in driven rain, only in prolonged rain, or every time, tells the survey a lot. Jot it down while it is fresh.
Do not do these
Stay off the roof. A wet flat roof is a fall risk, and a wet lantern offers nothing safe to hold. We never advise anyone onto a roof in the rain, and there is nothing useful to be done up there while it is wet anyway. The work that fixes a leaking lantern happens in dry conditions, from proper access, by someone insured to be up there.
- Do not apply sealant in the wet. Sealant will not bond to a wet, dirty surface, so it fails within weeks, and it hides the actual entry point from the survey, which makes diagnosis harder and the job bigger. It is wasted effort at best.
- Do not assume it is the glass. If a lantern leaks, the glass is almost never the cause. The failure is at the kerb or the flashing, and chasing the glass wastes time.
- Do not leave a tracked leak unlogged. Water can travel a long way along a rafter or under a covering before it drips, so where it appears inside is rarely directly below where it gets in. Photograph the internal path, not just the drip.
What to photograph for the survey
Good photographs let us understand the failure before we are on site, and sometimes narrow the cause before the survey. From inside and from ground level only, capture:
- Where the water first appears inside, and the track it follows down the reveal or bar.
- Any staining, misting between the panes, or perished, shrunken gaskets at the ridge and corners.
- The lantern from the garden at ground level, showing its size and how it sits on the roof.
- Whether the leak coincides with wind direction, if you can tell, since driven rain from one side points at a specific flashing lap.
Why this points to replacement, not a patch
A lantern that leaks only in heavy or driven rain has a detail that fails under load: a kerb too low at its lowest point, a flashing lap that lets driven water track back, or a covering that was stopped short and sealed rather than dressed over the kerb. Those are the failures that stay hidden in light rain and open up when water arrives horizontally, which on the Suffolk and north Essex coast it regularly does. A reseal touches none of them. It does not raise a low kerb, it does not lengthen a short flashing lap, and it does not dry out the timber that has usually been wet for years by the time water shows inside. We do not reseal or patch; we lift the unit, expose and inspect the kerb, rebuild the failed detail, and set a new lantern on it with a 10-year workmanship guarantee. How that diagnosis is made is covered on our leaking roof lantern diagnosis page, and why patching does not pay on our reseal or replace page.
Related questions
- Cracked roof lantern glass: is it safe? if a pane is damaged as well as leaking.
- How much does it cost to replace an existing roof lantern? for what the permanent fix costs.
- What time of year is best for fitting a roof lantern? because replacement runs all year, including now.
For why lanterns leak in the first place, see why roof lanterns leak, and the fitting detail that prevents it on what a roof lantern upstand is.
Get it surveyed as soon as the rain eases
A leaking lantern is genuinely urgent, so contain it now and get it looked at properly once conditions allow. Send us your photographs and where the property is, and we will survey it, find the failure, and give you one fixed price to replace it. Request a fixed quote for roof lantern replacement in Ipswich, Suffolk or north Essex.
Thinking about this job? We survey across Ipswich, Suffolk and north Essex and give you a fixed price before any work starts, with a 10-year workmanship guarantee.