The short answer
A cracked tile does not need replacing within hours, but it should be done soon, before the next hard frost or heavy rain. The tile below is often still shedding water through the underlay, which is why a crack can look harmless. Water and frost then widen it, and a single tile is swapped by lifting the ones above and sliding a matching tile in.
How urgent is a cracked tile?
It depends on the crack and on the roof underneath. A hairline crack in a tile that is otherwise lying flat may carry on shedding water for a while. A tile that has split right through, or has a corner missing, will let rain pass straight onto the layer beneath.
That layer is the underlay, a felt-like sheet on top of the rafters. The tiles hang on battens, thin timber laths nailed across it. Where the underlay is sound, a broken tile may cause no stain at all for a long time, which is why people leave the job. The underlay is not designed to take water continuously, and on older roofs it may be brittle, torn or missing entirely. Then rain reaches the roof space directly and lands on the timbers.
A sensible rule is to treat a cracked tile as a job for the next dry spell, not the next year. If you can see daylight through the crack from the loft, if there is a stain on the ceiling, or if more than one tile is damaged in the same area, call a roofer at once and make the roof safe for the night.
What happens if you leave it
Water finds the crack, and the crack gets bigger. Clay and concrete tiles both absorb a little moisture, and in freezing weather the water in a crack turns to ice and expands. Each cold night prises the split a little wider, until the tile breaks in two and the lower half slides down.
Beneath the tile, the batten is the next casualty. Wet timber softens, loses its grip on the nails, and eventually lets the neighbouring tiles slip. The damage then spreads from one tile to a patch of roof. Leaks that start this way can also travel, and our page on a leak that appears away from its entry point explains why the stain on the ceiling may be nowhere near the tile that caused it.
Moss, wind and the weight of snow all add to the load. A cracked tile is weaker than a whole one, and a gust that a sound roof ignores can lift it clear.
How one tile is replaced
Replacing a single tile is a small job when the roof is in decent order, and it follows a set sequence.
- Identify the type. Plain tiles hang on small nibs at their top edge, and interlocking tiles lock together at the sides. Which one you have decides the method.
- Lift the course above. On a plain-tile roof, the tiles above are raised slightly, using a wedge or a tool made for the job, so the broken one can be freed from its nibs. If the tile is nailed, the nail is cut or drawn out.
- Slide out the broken tile. The pieces come out, and the batten and underlay are checked for damage as they are exposed.
- Slide in the matching tile. The new tile hooks over the batten, sits at the right lap and is held with a clip or nail where the roof's design calls for one.
- Check the neighbours. The tiles that were lifted are lowered back, and the area is checked for others that have moved.
Slates are handled differently, because a slate is held by a nail hidden by the course above. A replacement is usually fixed with a small metal strap called a tingle, which is why a patched slate roof can show a scattering of them.
Matching the tile
The replacement has to be the right size, profile and colour, and on an older roof this is the hard part. Tiles weather, and a new tile beside a weathered one stands out. Reclaimed tiles often blend in better, which is why roofers keep a stock of salvaged ones.
Matching also affects the roof's life. A tile that is slightly too thick or too thin will not sit properly, and a mismatched tile can leave a gap where wind and water get in. If the building is listed, or lies inside a conservation area, the covering is part of what makes the building what it is, and a like-for-like repair is the sensible way to stay within consent. For what counts as a match, read about like-for-like roof repairs, which explains what is meant by a match, and where you should ask B&NES planning first.
If the tiles are not available in the original pattern, a nearby slope that is out of sight can sometimes supply them, with new tiles taking its place.
What it costs and when to look further
MyBuilder's 2026 roof repair guide puts minor repairs, covering a small leak or a few replaced tiles, at a typical £100 to £300 in the UK. Scaffold, access and the cost of matching materials all push the figure up. That is a national figure from a cost guide, not our price. We set our price once the survey is done, in writing.
One cracked tile can also be a sign of something wider. If several have broken in the same area, the cause may be a person walking on the roof, a fallen branch, a failing batten or a tile type that is reaching the end of its life. A repair patched tile by tile on a tired roof soon costs more than a larger repair done once.
Snow and ice cause this kind of damage in winter, and our page on whether to clear snow off the roof explains what to look for after a hard frost. For the full range of repair work in the area, see roof repairs in Bath. We survey for nothing and send photographs of the damaged area, and finished work comes under a 10-year written workmanship guarantee.
