A tiled roof is a tough covering and a forgiving one. It can lose a tile in a gale, shed a few grains of sand into the gutter and sprout moss on its shady side while still keeping the house dry for years. That is part of the difficulty. The early signs are easy to miss, easy to put off and easy to misread, and by the time water is coming through the bedroom ceiling the damage underneath is often well advanced. This guide sets out the signs in the order you are likely to see them, tells you what each one usually means, and explains how to separate a roof that wants a repair from one that is coming to the end of its life.
Checking safely from the ground
You can learn a great deal without leaving the pavement. Pick a dry, bright day and look at the roof from several sides with a pair of binoculars or the zoom on a phone. Look at the lines of the tiles first. They should run in straight, parallel courses. A tile that sits lower than its neighbours, or a row that waves, is a clue. Then look at the ridge along the top, the edges at the gable ends, the valleys where slopes meet, and the flashings round the chimney. Take photographs, so you can compare them in a year.
Do not go up. A roof edge is a long way up, tiles crack under body weight and wet tiles are slippery. Our answer on whether you can walk on roof tiles explains why a roofer with the right equipment is the only person who should be up there.
Slipped, missing and cracked tiles
The most obvious sign is a tile that is out of place. It may have slipped partway down the slope, leaving a gap at the top and exposing the batten and underlay. It may be missing altogether, with whole tiles turning up in the garden after wind. Or it may be cracked, with a visible line across the face or a corner broken off.
One slipped tile after a storm is usually a repair. A pattern is a warning. Tiles that slip in several places, or return to slip after being fixed, point to a fixing problem and not to bad luck. We explain the commonest cause in our guide to nail sickness, and the answer on what causes slipped roof tiles lists the others.
Daylight and damp in the loft
The loft tells you what the roof is doing. With a torch and the light off, look for pinpoints of daylight, which show where tiles have slipped or cracked or where the underlay has failed. Look at the underside of the tiles and battens for dark, damp patches, white mould or the sheen of condensation. Check the insulation: if it is stained, compressed or wet, water is getting in. Sniff for a musty smell, which is a sign of long-standing damp even when nothing is visible.
Also look at the underlay. A sagging, torn or perished membrane no longer catches the water that inevitably gets past the tiles in wind. Our answer on sagging roof felt explains when a droop matters. Stains on the ceilings below, brown rings that grow after rain, are a late sign that water has reached the room, and the reason they appear is covered in the page on water coming through the ceiling.
Moss, lichen and grit in the gutters
Moss and lichen on a roof look worse than they are. They grow on shaded and north-facing slopes, and a patch of moss does not by itself mean the roof is failing. What it does is hold water against the tiles, and in winter that water freezes and expands, which is how clay tiles flake and cracks widen. Heavy moss in the laps between tiles can also push water uphill.
Grit in the gutters is a different matter. Concrete tiles lose granules from their surface as they age, and a gutter or downpipe full of sand-coloured grit suggests the coating is wearing thin. Orange flakes in the gutter from a clay roof mean the faces of the tiles are laminating. Our answer on why clay tiles flake explains what is happening. Neither means an immediate replacement, but both mean the covering is entering the later part of its life. Cleaning is an option for moss, covered on the page about cleaning slate, clay and concrete roofs.
Sagging, dips and a wavy roof line
A roof that dips in the middle of a slope, or a ridge that is no longer straight, is more serious than a single tile. It suggests something structural: weakened rafters, battens that have lost their strength, a purlin that has dropped or walls that are spreading. A wavy roof can also be a sign that the roof was never built straight, and you can usually tell by comparing it with old photographs.
Do not leave this to chance. A sag can be minor and long-standing, or it can be progressing. Our answer on why a roof sags sets out the possible causes, and a survey will show whether the timbers are involved. If the sag is new or growing, treat it as urgent.
Failing details: ridge, verge, valleys and flashings
Many tiled roofs fail at the details before they fail in the field. The ridge is where mortar cracks and falls out, and loose or missing ridge tiles are one of the commonest storm losses. At the verge, along the gable edge, crumbling mortar lets wind and water in. In valleys, debris and worn linings cause leaks. Around the chimney, cracked mortar and lifting lead let rain run down the stack.
These are repairable in their own right, and they can be fixed without touching the tiles. Our pages on signs of ridge tile failure and roof valleys cover two of them in more detail. When the details are failing together, it is a sign the whole roof is aging in step.
How each material shows its age
The signs differ with the covering, and knowing which you have sharpens what you look for. Concrete tiles fade first, then roughen and shed grit, and their edges can chip. Clay tiles keep their colour but can flake on the face or crack in frost, particularly the older, softer sorts. Slate tends to fail at the fixings: the slate stays hard while the nail rusts, so slates slip, and the first sign is a slate lying in the garden. Pantiles and other curved tiles lose their ridges or crack along the curve. If you are unsure what is on your roof, our guide to plain and interlocking tiles helps you tell the two common formats apart, and concrete against clay shows how each ages.
Whatever the material, the pattern to worry about is the same one: faults that spread, repeat or appear in several places at once. An isolated flaw is wear. A cluster is a verdict on the roof.
Things that look like roof failure but are not
Not every stain or drip comes from the tiles. Condensation in a poorly ventilated loft can wet the underside of the roof and the insulation and send drips down walls in cold weather, with the roof intact. An overflowing or leaking gutter can soak the wall and the eaves and produce damp patches at the top of an outside wall that look like a roof leak. A failed seal around a rooflight or a cracked chimney flashing can send water in at a point that is nowhere near the tiles. Plumbing leaks in the loft, from a tank or a pipe, can make a stain on a ceiling that has nothing to do with the roof.
That is why a ceiling stain should be investigated and not assumed. Ask whether it appears only after rain (the roof), only in cold spells (condensation) or irrespective of the weather (plumbing). Our page on roof damp and condensation surveys explains how the sources are told apart.
How often to look
A good rhythm is a quick look from the ground twice a year, in spring and autumn, plus a look after any severe gale. Add a glance in the loft once a year with a torch. Keep your photographs so that changes stand out. Bring forward a survey if you see a pattern, if you are buying or selling a house, or if the roof is old enough that you do not know its history. A survey before a purchase is far cheaper than a repair after it, as our page on roof checks when buying in Basingstoke explains.
Repair or replace: reading the pattern
The question everyone asks is whether the roof needs replacing. The answer comes from the pattern of faults, not from any single sign. A useful way to read it:
| What you see | What it usually points to | Typical response |
|---|---|---|
| One or two slipped or cracked tiles after a storm | Isolated damage | Repair |
| Cracked ridge mortar or loose ridge tiles | Failed bedding | Re-bed or fit a dry ridge |
| Slips recurring across a slope | Corroded nails, weak battens | Strip and refix the area |
| Daylight and damp across a slope | Failed underlay and fixings | Strip and relay |
| Dip or sag in the roof line | Structural movement | Survey the timbers first |
| Widespread flaking or crumbling tiles | Covering at end of life | Recover the roof |
Age matters but does not decide. A 50-year-old roof in good order is fine, and a 20-year-old roof with bad workmanship may not be. What decides it is the condition of the fixings, battens and underlay as much as the tiles. Our pages on roof repair or replacement and signs your roof needs attention take that further.
What to do when you spot a sign
Write down what you saw and when. Photograph it from a safe place. If water is coming in, put a bucket under it, move belongings and, if it is near light fittings or sockets, keep clear and switch off at the consumer unit if it is safe to do so. Then arrange a survey. Small faults get bigger in winter, because frost and wind work on any gap. A repair booked now is cheaper than a repair booked after the ceiling has come down. Our guide to tiled roof repair costs gives sourced ranges for the work that follows.
How we assess a tiled roof
We start in the loft and finish on the roof. We check the underlay, battens, rafters and fixings, lift a few tiles where the pattern suggests it and photograph everything we find on your roof. The written report separates what needs doing now from what can wait, says plainly if the roof has years left, and quotes for the repair when a repair will do. The quote is fixed. Any repair we carry out is covered by our written guarantee on workmanship, which runs for ten years, and we take the waste away with us. Learn more on our page about pitched roofing in Basingstoke, or call 01256 213956.
