Most roof leaks come from a few common weak points: slipped, cracked or missing tiles; worn or split flashings around chimneys, walls and dormers; loose ridge or verge mortar; blocked valleys and gutters; and cracked or blistered flat roofs. Sometimes what looks like a leak is actually condensation. Water can travel along timbers before it drips, so the stain on your ceiling is not always directly below the cause.
What to do straight away
- Catch the water with buckets or bowls and move furniture and belongings out of the way.
- Keep away from electrics. If water is near light fittings or sockets, turn off the power to that area at the consumer unit and call an electrician if needed.
- Check the loft with a torch, if it is safe, to see where water is coming in.
- Do not go up on the roof, especially in wind or rain.
- Take photos of the damage for your records and your insurer.
If water is coming in fast after a storm, our guide to storm damage: what to do first has more detail.
The common causes
Slipped, cracked or missing tiles and slates
The most common cause. Wind lifts tiles, frost cracks them, and on older roofs the nails or pegs that hold them rust or wear out. Even one gap can let rain onto the underlay, and if the underlay is old or torn, into the loft.
Worn flashings
Flashings seal the joins where the roof meets a chimney, wall, dormer or extension. Lead can split, mortar fillets crack, and sealants fail. Leaks at these joins often show up on walls or ceilings near the chimney breast or the side of a dormer.
Ridges, hips and verges
Mortar on ridge, hip and verge tiles breaks down with age and weather. Once it cracks, tiles can loosen and water can run underneath. These leaks often appear after windy, wet weather.
Blocked or damaged valleys
Valleys collect water from two slopes. Leaves, moss and debris can block them, and old lead or mortar valleys can split. Water then backs up under the tiles.
Gutters and downpipes
Blocked or sagging gutters overflow, sending water down walls or back under the roof edge, where it can get into the eaves and rot timber fascias. See our guide on why gutters overflow.
Flat roofs
Old felt cracks, blisters and splits, and water ponds where the falls are poor. Leaks often start at the edges, upstands and around rooflights rather than in the middle of the roof.
Chimneys
Porous brickwork, failed pointing and cracked flaunching on top of the stack can all let water in, as can an uncapped flue. Chimneys that are no longer used still need looking after, and a chimney leak often shows as damp on the chimney breast inside, sometimes in rooms well below the loft.
Dormers and extensions
The joins where a dormer or extension meets the main roof are a classic weak spot. Dormer cheeks, the flashing along the sides and the flat tops of dormers all take a lot of weather, and leaks here often show up inside the room below rather than in the loft.
Roof windows, vents and pipes
Anything that passes through the roof needs to be sealed. Worn flashing kits around roof windows, cracked seals around soil pipes and poorly fitted vent tiles can all let water in.
Condensation
Warm, moist air from the house can condense on the cold underside of the roof, especially in a poorly ventilated loft. This drips onto insulation and ceilings and is easily mistaken for a leak. Clues include damp spread evenly over the underlay, rather than in one spot, and problems in cold weather rather than in rain. Bathrooms and kitchens without good extraction make it worse.
Narrowing it down
- Only in heavy rain? Think gutters, valleys and flashings.
- Only in wind-driven rain? Think ridges, verges, slipped tiles and flashings on the exposed side.
- In cold weather, without rain? Think condensation.
- On a flat-roofed extension? Think the felt itself, the edges and where it meets the wall.
Getting it fixed properly
Avoid quick fixes such as smearing sealant over a crack on the outside. It can trap water, hide the real cause and make a proper repair harder. A good roofer will find where the water is actually getting in, fix the cause and check for any damage to battens, underlay and timbers.
In Essex, Hertfordshire and Cambridgeshire
Local conditions make some causes more likely than others.
- In Clacton-on-Sea and West Mersea, strong winds and salt air lift ridge and hip tiles, loosen verges, rust metal fixings and break down old mortar faster than inland.
- In Chatteris, roofs catch the wind across the open fen from every direction, so lifted ridges and verges and lost slates are common after a storm.
- In Loughton and Buckhurst Hill, Epping Forest means lots of leaves, twigs and moss, so blocked gutters and valleys are a frequent cause of overflowing water.
- In Ware, homes near the River Lea sit in damper air, which wears out mortar and lead over time, so worn chimney flashing and blocked valleys are common on older roofs.
How First4Roofcare can help
We find the cause, not just the symptom, and show you photos of what we find. For a leak that can wait for a survey, see our roof repairs and gutter repairs pages. For water coming in now, our emergency roofing service will make your roof weather-tight as soon as we can. Otherwise, book a free survey.