- A roof leak often shows some distance from the place where water gets in, because the water runs along the underlay and the roof timbers before it drips, so the source is usually higher up the slope than the stain.
- The usual sources of a roof leak are slipped or cracked slates and tiles, flashings at chimneys and walls, valleys, worn felt, flat roof joints and overflowing gutters.
- If a damp patch on a top-floor ceiling grows during or after rain, the roof is the likely cause. If it gets worse when water is being used, rule out plumbing with a water meter test, and if it follows cold nights rather than rain, suspect condensation.
- You can look for the cause safely from the ground with binoculars during or just after heavy rain, and from the loft with a torch while standing on crawl boards or the joists, never the plasterboard. Never go on the roof to look.
What are the signs of a leaking roof?
The clearest sign is a damp patch or stain on a top-floor ceiling, or high on a wall, that appears or grows when it rains. Others are paint lifting near the ceiling, drips from a light fitting, a musty smell in a room under the roof and damp timber in the loft.
Checkatrade notes that a leak sometimes shows only after several days of bad weather rather than in the first shower. Outside, the National Lottery Heritage Fund says broken slate or tile on the ground can point to a problem, so check the path and the garden.
If water is pouring in, the ceiling is bulging or water is near a light fitting, treat it as an emergency. Turn off the power to that area at the consumer unit if it is safe to, keep out from under a bulging ceiling, and call a roofer straight away. Our storm damage guide covers the first 24 hours and insurance claims.
Is it definitely the roof?
It is probably the roof if the patch gets worse during or after heavy rain, is in a top-floor room, or sits near a chimney or a rooflight. Checkatrade suggests plumbing instead when the leak gets worse as water is used, shows up when it has not rained, or sits under a bathroom or kitchen. A blocked or faulty overflow on a loft tank or cistern can also bring water through a ceiling.
- Check the water meter. If you have one and can reach it safely, Yorkshire Water's test is to leave the inside stop tap fully on, switch off anything that uses water and note the reading, then use no water for at least 30 minutes and read it again. If the readings differ, you probably have a leak inside the home.
- Check the boiler pressure. A leak on the heating pipes may not show on the meter. If the pressure keeps dropping, Worcester Bosch advises checking every visible joint, including radiator valves, and seeing whether the pressure relief pipe on the outside wall is dripping.
If either test points to a pipe, you need a plumber or heating engineer, not a roofer.
Condensation is the other common mix-up. NHBC guidance, written for new homes, says most roof-space condensation is temporary and happens when it is cold outside, when the weather turns from warm to cold, or when nights are much colder than days. A patch that follows cold nights rather than rain points that way. Our damp patch guide covers condensation in detail.
Why does the water come through away from the leak?
Water that gets past the slates or tiles runs along the underlay and the roof timbers before it drips, and comes through the ceiling wherever it first finds a way down. Checkatrade says the drip inside is not always directly below the entry point, and a roofing contractor quoted in the Yorkshire Evening Post in 2017 said water can travel several metres in a loft before it shows.
A June 2025 article in Roofing Cladding & Insulation magazine says rain driven by the wind will get past the outer slates or tiles, and that the underlay beneath should sag slightly between the rafters to carry that water down to the eaves. Where the underlay is pulled tight, water can pool behind the battens and get in through the nail holes that fix them, which the article calls one of the most common places for water to get below the membrane.
So the stain tells you where to start looking, not where the hole is: the source is usually higher up the slope. For North, West and South Yorkshire, the Met Office says the strongest winds nearly always come from between south and north-west, while long spells of rain are often linked to east or north-east winds. A leak that only shows in one kind of weather points to whichever slope or chimney face takes it.
Where do roof leaks usually come from?
Most roof leaks start at one of a few places: slipped or cracked slates and tiles, flashings at chimneys and walls, valleys, worn felt, and the joints of flat roofs.
Slipped or cracked slates and tiles
Bradford Council describes blue Welsh slate as synonymous with the Victorian rebuilding and expansion of the district's towns and villages, and it is still on terraces across Yorkshire. Cadw, the Welsh Government's historic environment service, says a common cause of slipped slates is the iron nails holding them rusting through, which is known as nail sickness. Bradford adds that slates which easily break apart can hold water like a sponge and let it soak into the timbers. Concrete tiles on post-war estates crack and slip too, often after storms.
Flashings and chimneys
Flashings are the strips of lead, or sometimes zinc, that seal the joint where the roof meets a chimney or wall. Bradford Council advises replacing defective lead or zinc flashings along with the soakers that tuck under the slates. It also warns that the flaunching, the mortar around the chimney pots, decays quickly.
Valleys
A valley is the internal angle where two slopes meet. Kirklees Council lists valleys among the weak spots of older buildings and warns that if they fail, the roof timbers are likely to decay. Cadw says tape and mastic are suitable only for very temporary emergency repairs to lead valleys.
Felt, ridges and flat roofs
Worn felt or underlay lets through the water that gets past the slates. The Heritage Fund notes that ridge and hip mortar eventually fails and lets water in, and our BS 5534 guide explains how ridges should be fixed now. On flat roofs over extensions and dormers, water tends to get in at the laps and edges or where the roof meets the house wall, then runs under the covering before it shows.
Gutters
A blocked or broken gutter can spill water over the roof edge and into the wall, which looks like a roof leak from inside. Our gutter cleaning guide covers keeping them clear.
What can you check safely from the ground?
From the ground you can safely check the slates or tiles, the ridge, the chimney and the gutters with binoculars, and you should never go on the roof to look. The Heritage Fund suggests looking during or just after heavy rain, when you can see whether the gutters and downpipes are coping, and working over each face of the house from the roof downwards. Cadw adds that a nearby first-floor window, such as a neighbour's, often gives the best view of your roof. Look for:
- gaps in the slates or tiles, or a slate sitting lower than its neighbours
- gaps along the ridge, or lead lifting where the roof meets a chimney or wall
- cracked pots or crumbling flaunching on the chimney, or a stack that leans
- gutters that overflow or drip at the joints
- patches of wall getting soaked in wet weather, which Bradford Council says show the rainwater system is leaking
- large areas of moss, which the Heritage Fund notes can hold moisture (our moss guide explains when it matters)
Take photos as you go. Leave ladders and roof work to a contractor: Cadw advises homeowners not to carry out their own roof repairs unless they have the right equipment and know how to use it safely.
What should you look for in the loft?
In the loft, look for a wet trail: damp or stained timber, wet patches on the felt, water marks on the insulation, and daylight where there should be none. Checkatrade advises going up only if it is safe and dry underfoot, and keeping your hands off the electrics. B&Q's loft safety advice adds:
- Never stand on the plasterboard between the joists, which will not take your weight. Use crawl boards laid across the joists, not overhanging too far or resting on cables or pipes.
- Take proper light, such as an inspection lamp or a head torch, and have someone hold the ladder steady while you climb.
- Wear an FFP3-rated dust mask, with gloves and goggles, if you move insulation.
Start above the stain and work up the slope, following the marks on the timber and felt to where they begin. Checkatrade suggests circling the damp area in chalk and measuring from a fixed point such as the chimney stack or a vent, so a roofer can find the same spot from outside. Check the cold water tank and its overflow while you are up there. Do not try to seal the leak permanently from inside, which Checkatrade warns can send the water somewhere else and worsen hidden damage.
When should you call a roofer?
Call a roofer once you are fairly sure the water is coming from outside, and straight away if water is pouring in, the ceiling is sagging or the roof is open where slates or tiles are missing, which Checkatrade treats as emergencies. Do not leave small leaks either: Spelthorne Borough Council's guidance on historic roofs notes that wet rot is commonly found where water has been getting in for a long period.
Give the roofer your photos and chalk measurements, and a note of when it leaks and which way the wind was blowing.
Be wary of anyone who knocks to say they have spotted a problem. After storms Malik and Corrie in February 2022, trading standards at the then North Yorkshire County Council told residents to turn away cold callers, and said officers had found past cases of traders carrying loose tiles around to convince people their roof was damaged.
Roofline offers free inspections across Yorkshire. We photograph what we find and give you a free, itemised quote. Call 07413 797731, send photos by WhatsApp to the same number, or book an inspection.
This guide is general information about roofing in England and is not a substitute for advice about your own roof. Standards and regulations are updated from time to time; check the current edition before relying on a specific requirement. Written by Roofline, roofers across Yorkshire. Last reviewed September 2026.
