When water comes through a ceiling, the damage you can see is rarely where the trouble starts. Rainwater gets in at one point on the roof, runs along a rafter or the underside of the felt, and appears metres away as a brown ring above the landing or a drip beside the bedroom light. That distance is why guessing at the cause wastes time. This guide sets out what to do in the order that matters: protect people and wiring, limit the damage, decide whether the roof or the plumbing is responsible, and then get the real source dealt with.
The first ten minutes: people, electrics, then water
Start with electricity. Water and wiring in the same ceiling void is the one genuinely dangerous part of a leak, because ceiling roses, downlights and loft cables sit exactly where the water collects. If water is dripping from or near a light fitting, switch that lighting circuit off at the consumer unit (the fuse board) and leave it off. Do not flick the wall switch to test it. Keep out of the room if the plaster is sagging or if water is running down the wall near sockets. Our short note on a roof leak near electrics goes through what to leave alone.
Next, deal with the water itself. Move furniture, rugs and electronics out from under the stain and put a bucket or a washing-up bowl below the drip, with a towel in the bottom to stop splashing. If the ceiling is bulging, plasterboard is holding a pocket of water that is getting heavier. A bulge will often fail suddenly, so keep people out from underneath it. Pushing a screwdriver through the lowest point of the bulge, with a bucket directly beneath, lets the water out in a controlled stream rather than letting the whole section come down. There is more on that in our answer on a bulging ceiling from water.
Finally, take photographs and a short video of the stain, the drip and any damage before you move or clear anything. You will want them for a roofer, and for an insurer if you claim. Note the time and what the weather was doing.
Reading the stain before you call anyone
A little detective work saves a lot of money, because it tells the roofer where to look and tells you whether to call a roofer or a plumber first. Ask four questions.
- When does it drip? If it only appears during or just after rain, the source is almost certainly the roof, the chimney or the gutters. If it drips in dry weather as well, think plumbing, a leaking tank or condensation.
- Does it follow the wind? Water that appears only when the rain is driven from one direction usually points to a gap on that slope, such as a slipped tile, a lifted flashing or a failed verge. Our answer on a roof that only leaks in wind explains why.
- How big and how fast? A slow ring that grows over days is often a small, steady entry. A sudden flow after a storm points to storm damage or a blocked valley overflowing.
- What is directly above? A bathroom, an airing cupboard or a header tank above the stain makes plumbing a strong suspect. A chimney breast, a valley or a flat-roof upstand makes the roof the suspect.
Water that enters a pitched roof usually runs down the underlay (the waterproof sheet under the tiles) until it meets something that lets it through, such as a batten joint, a rafter or the top of an internal wall. It then follows timber sideways and downwards. On a typical semi it is quite possible for the entry point to be a full tile-width higher and a couple of metres to one side of the stain. Bear that in mind before anyone starts pulling up carpet or cutting plaster directly under the mark.
Roof or plumbing: tests you can do safely
Most ceiling leaks turn out to be roof-related, but the plumbing check takes five minutes and rules out a call-out that cannot help. Look at the water meter if you have one: switch off every tap and appliance, then watch whether the dial still moves. A moving dial in dry weather means a pipe is leaking somewhere. Check the cold water storage tank in the loft if you have one, looking for a failed float valve with water running out of the overflow pipe, and look at the pipe joints and the underside of the tank for drips.
Radiator and heating pipes under the floor above the ceiling are another source. A leak from a central heating pipe is often discoloured and may smell stale, whereas rainwater is clearer. A bath or shower that has lost its seal, or a toilet waste joint, drips only after use, which gives it away.
Condensation can mimic a leak, particularly in winter. Warm, damp air from kitchens and bathrooms rises into a cold loft, meets chilled roof timbers and the underside of the underlay, and condenses into drops that fall onto the insulation and soak through the ceiling. It tends to affect larger areas, shows up in cold snaps rather than downpours, and often comes with black mould on rafters. That is a ventilation fault, not a hole in the roof, though a roofer can tell you which in one visit. Our note on whether a roof leak can cause mould covers the overlap.
What on the roof lets the water in
Once the roof is the prime suspect, these are the faults we trace most often. The table lists the cause, how it tends to show indoors, and what the repair usually involves.
| Cause on the roof | How it shows indoors | Usual repair |
|---|---|---|
| Slipped, cracked or missing tiles | Isolated drip or stain below a slope, worse in wind-driven rain | Re-seat or replace tiles, check the battens and underlay beneath |
| Failed lead flashing at a chimney or wall | Stain on the chimney breast or along the wall line | Re-dress or replace the flashing and re-point the chase |
| Blocked or worn valley | Heavy flow after sustained rain, often an upstairs corner | Clear the valley, replace damaged lead or valley liner |
| Crumbled ridge mortar | Stain along the top-floor ceiling beneath the ridge | Re-bed or mechanically re-fix the ridge tiles |
| Flat roof upstand or outlet failure | Drip under an extension, often beside a wall | Re-form the upstand, renew sealant or patch the membrane |
| Overflowing gutter or leaking joint | Damp patch near an outer wall or window | Clear, realign or replace the gutter run |
A flashing is the strip of lead or other metal that bridges the join between the roof covering and something that rises through it, such as a chimney. A valley is the V-shaped channel where two roof slopes meet and funnel water. Both carry a lot of water in a downpour, and both fail through age rather than weather alone. Lead moves with heat and cold, and when the mortar holding its top edge crumbles, rain gets behind it. If you suspect the stack, our guide on finding and fixing a roof leak shows how we trace it.
Stopping it from the outside
You can limit damage from the inside, but only work on the roof stops the leak. Climbing a wet, steep or old roof to look for the problem is a common way to end up in hospital, and an amateur on a ladder can see little that a roofer with proper access cannot. Our answer on whether to go on the roof to check damage is blunt about this: look from the ground with binoculars, and leave the rest to someone with the equipment.
When we attend a ceiling leak, we make the roof safe first. That usually means a temporary measure over the opening, such as lifting and re-bedding a tile, fitting a patch or sheeting over a damaged area, so the house stays dry while the proper repair is arranged. Read how temporary roof repairs work and how long they are meant to last. A tarpaulin is a holding measure, not a repair.
The proper repair follows once we can see the roof dry and in daylight. We look at the underlay beneath the damaged area, because a tile that slipped may have let water run for weeks and soaked the battens and rafters. We check the loft from inside for dark, damp timber and wet insulation, and photograph all of it so you can see your own roof's condition. Where a repair is enough, we say so and quote it as a fixed written price. Where the roof is worn out across a wider area, we show you that on the photographs as well, and explain the options without pushing a replacement. Typical UK call-out figures run from £150 to £350 before materials. Your fixed quote follows the survey.
Drying out, ceiling repair and records
Once the water has stopped, the ceiling has to dry. Do not paint over a stain until the timber above and the plaster below are properly dry, or the mark will bleed through and the damp will keep feeding mould. Open the loft hatch if it is safe to do so and let air move through the area. A dehumidifier in the room below helps, and a fan heater on a low setting dries the surface but not the void, so do not rely on it alone.
Wet loft insulation loses most of its value until it dries and may need replacing. A plasterboard ceiling that has sagged or stayed soaked will usually have to be cut out and replaced, since it loses its strength once saturated. Lath and plaster ceilings in older homes behave differently: the plaster keys can break away from the laths, and a patch may crumble days after the leak appears to have stopped. Treat both as jobs for a plasterer once the roof is sound.
Keep the photographs, the dates and any quotes together. Insurers generally want to see the cause and date of damage, and the difference between sudden damage and long-term wear can affect a claim. Our note on roof damage evidence for insurers lists what to gather. For the wider question of when a leak counts as urgent, see what counts as a roof emergency.
Getting help and what to expect
If water is coming in now, ring us on 01256 213956 or send a WhatsApp with photographs of the stain and the weather conditions. We prioritise emergency calls and aim to make a leaking roof safe first, then explain the cause and the repair. For the wider range of help we offer, see our emergency roof repairs in Basingstoke page. If the same ceiling has marked more than once, that is a sign of a repeat fault, so ask the roofer to show you the entry point on a photograph rather than accepting a patch of sealant over the top.
