You didn't notice it at first. Then a little. Now you look at it every night from bed.
There's something reassuring about a damp patch on the ceiling: it doesn't do anything. It just sits there. Until it rains.
Short answer: what does a damp patch on the ceiling usually mean?
Is the patch on the top floor and does it get bigger or darker after rain? Then your roof is leaking. Usually the cause is a cracked or shifted roof tile, worn lead flashing around the chimney or dormer, a loose ridge tile or a crack in the covering of a flat roof. First work out when the patch gets wet and what is directly above it. A blocked gutter you can fix yourself. For anything that requires going onto the roof, have a roofer find and fix the leak. Not because it can't be done, but because a wet, sloping roof is no place to try something for the first time.
How do you recognise a roof leak?
The cause is outside, but the evidence is inside. These are the signs:
a yellow or brown ring on the ceiling of the top floor;
a patch that grows during or just after rain, and seems to "rest" in dry weather;
drips or wet insulation in the loft;
flaking paint, loose plaster or a bulge in the ceiling;
damp near the chimney, dormer, skylight or along the edge of the roof;
a musty smell in the loft, or dark patches on the beams;
on a flat roof: standing water after rain, or blisters in the roofing.
Recognise two or three of these, and do they show up after rain? Then you know enough.
What are the possible causes?
Not every damp patch has the same cause. These are the most common ones, in order of likelihood.
1. Cracked or shifted roof tile
The classic. One tile shifts a few centimetres in a storm, and that's all it takes. Water runs past the tile onto the roof boarding and ends up on your ceiling via the insulation.
How to recognise it: the patch appears suddenly after a storm, sits under one specific section of roof, and from the street you can see a tile missing or lying crooked.
How likely: high, certainly on roofs that have been around a while. Replacing the tiles is usually the fix.
2. Worn or detached lead flashing
Around the chimney, dormer and skylights there is lead that keeps the joint watertight. Lead expands in summer and shrinks in winter. After twenty years it has had enough.
How to recognise it: the patch is close to the chimney, dormer or skylight and the leak didn't come out of nowhere, but slowly got worse.
How likely: high on roofs older than 15 to 20 years.
3. Loose or cracked ridge tiles
The ridge tiles on top of the roof are fixed with mortar. That mortar crumbles. After that, water can get in under the ridge.
How to recognise it: the patch is high up in the roof space, in the middle of the loft, and you find bits of mortar in the gutter or on the patio.
How likely: medium, especially in older houses.
4. Leaking flat roof
On a flat roof the suspects are different: a crack or blister in the bitumen or EPDM, a blocked outlet that leaves water standing, or a poor joint at the roof edge or around a pipe.
How to recognise it: the patch is under an extension, garage or dormer, and hours after rain there is still water on the roof.
How likely: high on flat roofs older than 15 years. A local repair of the bitumen is often enough.
5. Blocked or overflowing gutter
A gutter full of leaves overflows. The water then doesn't go down the downpipe, but behind the fascia and into the roof.
How to recognise it: the patch is along the outside wall or roof edge and you can see the gutter overflowing when it rains.
How likely: medium. In October and November: higher.
6. Condensation (no leak)
Sometimes nothing is leaking at all. Warm, moist air from the house condenses against the cold roof boarding and drips down. Mainly in winter, mainly in poorly ventilated lofts.
How to recognise it: the patch also gets wet in dry but cold weather, and isn't clearly under a tile, pipe or chimney.
How likely: lower, but don't rule it out before you send someone onto the roof.
How can you find out what's going on yourself?
You don't need to get onto the roof to get a long way. This is what you can safely do, from the ground or from a solid loft floor.
Look at what is directly above the patch. Chimney, dormer, skylight, ridge or roof edge? That immediately points you in a direction.
Watch the timing. Does the patch grow during or just after rain? Leak. Does it also get wet in dry, cold weather? Then think condensation.
Walk around the house. Check whether any tiles are missing, crooked or broken. Binoculars help. The neighbours are watching anyway.
Go into the loft with a torch while it's raining. Follow a dark trail or glistening water up along the roof boarding. The leak is almost always higher than the patch itself.
Check the gutter and the outlet. Is the gutter overflowing? Is there water on the flat roof that isn't going anywhere?
Look at the ridge. Bits of mortar in the gutter or on the ground say enough.
What you don't do: get onto the roof yourself. A wet, sloping roof is slippery, tiles break under your feet and you fall further than you think. Also leave the ceiling alone and don't pull out insulation if there is wiring nearby or the ceiling is already sagging.
Should you fix it yourself or have it fixed?
Do it yourself
Some things you can simply do yourself. A gutter on the ground floor you can empty with a ladder, a bucket and half an hour. So can a blocked outlet on an easily reached flat roof over the extension. Is the patch under a skylight and can you see the rubber seals around it are dirty? Clean them carefully and see if it stops.
Turns out to be condensation? Then the fix is ventilation. Open the vents, air the loft daily, keep the bathroom door closed when showering.
When does it get too complex?
As soon as you have to get onto the roof, that's where it ends. Replacing tiles, repairing lead, refixing a ridge tile or repairing a flat roof needs the right materials, fall protection and someone who has done this more than once. You don't see a mistake straight away. You see it during the next rain shower, in the same spot, slightly bigger.
Can you do it yourself? Maybe. Are you going to do it this weekend? That's what you said last weekend.
Have it fixed
A roofer finds the cause, repairs the tile, the lead, the ridge or the roofing and checks whether the roof is watertight again. That last part is the difference with painting over the patch inside: that looks fine for a while too.
When should you call a professional quickly?
Not every patch is urgent. These are:
water is actively dripping or running in;
the patch is visibly bigger within a day;
the ceiling is bulging, sagging or plaster is coming down;
water is getting near lights, sockets or the cabling of your solar panels;
tiles are missing after a storm, or one is hanging loose;
you can't find the cause;
the leak comes back after an earlier repair.
In autumn and winter that counts double. Every shower puts fresh water into your roof, and in frost that water expands in exactly the crack you'd rather not see get bigger.
How does a roofer fix the problem?
Many people don't book because they don't know what happens next. This is it, in four steps:
Locate. The roofer looks at the patch inside, inspects the loft and then goes onto the roof. The leak is often a good deal higher than the patch, because water runs down the roof boarding before it comes through your ceiling.
Identify the cause. Tile, lead, ridge, flat roof or outlet. You hear what's going on and what's needed. No jargon, just: this is it, this is what we're going to do.
Repair. Tiles are replaced, lead and zinc work is renewed, the ridge tile is refixed or the flat roof is repaired locally.
Check. Is the roof watertight again? And is there a second weak spot that will do the same thing in three months?
Then it's done. Not spectacular. But dry.
What happens if you do nothing?
You can wait another week. Or until after winter. The patch is in no hurry.
The water is. Meanwhile it quietly works its way further into your roof, and over time that leads to:
wet insulation, which no longer insulates and never dries out;
rot in the roof boarding, purlins or rafters;
mould in the loft and in the ceiling, with a musty smell you stop noticing after a while, but visitors don't;
plaster and ceiling that come loose or come down;
short circuits if the water reaches wiring, lights or the inverter of your solar panels.
Replacing a roof tile is a small job. A rotten roof structure isn't. The difference is mostly how long you've been looking at it.
How do you prevent a roof leak?
Have your roof inspected every few years, and always after a heavy storm.
Empty the gutters and the flat-roof outlet twice a year. At the very least in autumn, once the trees are done.
Take a look now and then at the lead around the chimney, dormer and skylights. Cracks and lifting are visible from the ground.
Keep the flat roof clear of leaves and moss, so the water has somewhere to go.
Ventilate the loft. Condensation isn't fond of ventilation.
A 25-year-old flat roof is not "still fine". Have it renewed in time.
Frequently asked questions
Can a damp patch on the ceiling disappear by itself?
The patch dries out in nice weather. The cause doesn't. With the next shower it's back, usually a bit bigger.
How do I know whether it's coming from the roof or from somewhere else?
Top floor plus growing after rain: the roof. A bathroom or water pipe above it and also wet in dry weather: then you want a plumber, not a roofer.
Can a damp patch appear without a leak?
Yes. Condensation against cold roof boarding causes drips, especially in poorly ventilated lofts in winter. The difference: condensation also appears in dry, cold weather and isn't clearly under a tile or pipe.
Who should I call for a roof leak?
A roofer. Through Zoofy you book one who has been vetted in advance, you see the price up front and you pay once the roof is watertight. No six messages and someone who can come "Tuesday, between eight and five".
Can I repair a roof leak myself?
A blocked gutter or outlet, yes. Tiles, lead, ridge or roofing, no. For those you have to get onto the roof, and that is exactly the job you don't want to do yourself.
How quickly does a roof leak need to be fixed?
As soon as possible. While it leaks, the insulation gets wetter and the timber doesn't get drier. Is it actively dripping? Then book today.
Does my insurance cover a roof leak?
The consequential damage inside (ceiling, floor) often is, if the cause was sudden, such as a storm. The roof itself usually isn't, if it's wear and tear. Check your policy; it saves an argument afterwards.
Have your roof leak fixed through Zoofy
You probably now know where it's coming from. You also know you can't reach it yourself.
So you can wait a bit longer for a dry week. Or you book a roofer through Zoofy. You choose the job and a time that suits you. We arrange a professional who has been checked in advance. You see the price up front, and pay once the roof is watertight.
The patch dries out. This time for good.