Walk almost any street in Bath and the skyline of the roofs is drawn by ridge tiles. They cap the line where two slopes meet, and they come in a handful of familiar shapes: rounded, peaked, decorative with a raised crest, and in some places a glazed blue-grey clay. To a roofer the differences matter a great deal. A replacement that is the wrong size will not sit on the tile below it, and one in the wrong colour will show from the pavement for years. If you have lost a tile in the wind, or you are comparing quotes, it helps to know what you are looking at. The common types are easy to tell apart once you know which features to check, yours can usually be identified from the ground or from a photograph, and a replacement is matched so that the repair looks like part of the roof and not a patch on it.
Half-round ridge tiles
The half-round ridge is the one most people picture. It is a curved tile, the shape of a split pipe, set over the apex, open side down. Each tile overlaps its neighbour at a joint, and the finished run is smooth and continuous. You can buy half-round tiles in clay or concrete, and they suit both plain tiles and the flowing profile of pantiles or double Romans.
You can usually spot one by the soft rounded outline against the sky and by the regular joints every foot or so. The tile is simple, which is why it is so common, but simple does not mean interchangeable. The radius of the curve differs between makers. A tile with a slightly flatter curve will rock on its neighbour. A tile that is a few millimetres wider leaves a gap along the sides where wind can get under.
On a roof dressed with mortar, the half-round tile is bedded in a continuous strip and the ends are closed off with mortar pointing. On a dry-fixed roof the tile is held by clips and a central fixing, with no wet joint at all. The two methods use the same tile, but the way it is fixed changes how a loose one is repaired. Our page on replacing a single ridge tile covers the sequence for a lone failure.
Angled ridge tiles
An angled ridge has two flat faces meeting at a sharp peak, like a small gable laid along the top of the roof. Compared with a half-round it looks crisper and gives the roof a more defined line. You see it on many twentieth-century houses and on roofs covered in flat plain tiles, where its straight faces sit well against the straight courses below.
Angled tiles are made in more than one internal angle, so that the tile can follow the pitch of the roof. A steep roof needs a narrower peak, a shallow roof a wider one. That is the point most often missed by anyone ordering a replacement from a photograph. If the angle is wrong, one edge of the tile stands proud of the roof and leaves a V-shaped gap that lets in rain and wind-driven snow.
The same shape appears on hips, the sloping lines at each corner of a hipped roof, and at the foot of a hip there is often a hip iron, a metal bracket that stops the lowest tile slipping. Angled hip tiles are cut at the bottom end to sit on the eaves course, and a good hip is neatly mitred where it joins the ridge. When we replace a damaged hip tile, we match both the ridge profile and the cut so the joint is tight.
Crested and decorative ridges
A crested ridge has a raised decorative line along the top, which can be a plain fin, a scalloped edge or a pattern of cut shapes. Victorian and Edwardian builders used crested clay ridges to give a roof some ornament, and villas and terraces from those periods often still carry them. The crest is part of the tile, not an addition, so every tile in the run carries a piece of the pattern and the joints must line up if it is to read as one decoration.
That makes crested ridges the hardest type to repair. If a crest is chipped or a tile is lost, a match has to be found with the same height, the same pattern and the same repeat. Modern catalogue crests are often close but not the same, and a near match will show as a break in the rhythm. For that reason we look first at salvaged tiles, which have the right weathering as well as the right shape. Our page on reusing ridge tiles explains when old tiles can be lifted, cleaned and relaid.
If a run of crest is too damaged to match, a decision is needed about the whole length: replace it with a new run in the nearest available pattern, or re-form the ridge in a plainer tile. On a listed building neither is a decision for the roofer alone, because the ridge is part of the building's character and the council may want to see the proposal.
Blue ridge tiles
Blue ridge tiles are made of dense clay fired to a dark blue-grey colour, often with a smooth or slightly glossy surface. They are associated with engineering clay, the same hard, low-absorption material used for blue bricks, and they sit well on natural slate, where the cool colour sets off the grey of the roof. The tile is usually half-round or angled, and sometimes crested, so blue describes the colour and finish and not the shape.
Because the colour comes from the firing and not from a coating, a blue tile does not fade the way a painted or concrete tile can. What it does is pick up moss and lichen in the joints and on the upper face over time. A pale replacement against an old blue run is therefore obvious in a way that is hard to fix after the event.
Matching a blue tile means checking three things: the shade, which varies between kilns; the surface, smooth or textured; and the dimensions, because blue tiles from different makers are not the same length. Where an exact match cannot be found, a good option is to take tiles from a less visible stretch, such as the back slope or the end by a chimney, and use them on the front, then fill the hidden stretch with the new ones.
Clay, concrete and stone ridges
The tile type is one question, and the material is another. Ridge tiles on Bath roofs are made of clay, concrete or stone, and each behaves differently.
Clay
Clay is fired and holds its colour. It weathers gently, and old clay ridge tiles are often still sound after the mortar beneath them has failed. That is why lifting and rebedding old clay is common. The usual enemies are frost, which can crack a tile that has soaked up water, and impact from a fall of slate or a dropped tool.
Concrete
Concrete ridge tiles are heavier and cheaper. The colour is a coating over the surface and fades as the weather wears it. Concrete tiles are usually matched to a concrete roof tile of the same make, and the ranges have changed over the years, so a tile from today's catalogue can look different from one laid some time ago.
Stone
Stone ridges are cut or carved from a block and are used on stone-tiled roofs, where a clay or concrete ridge would look wrong. They are heavy, and each one is bedded and fixed with care. A lost stone ridge is often replaced by taking a similar one from elsewhere on the roof or from a salvage yard, since new carved stone is a slow and specialist order.
Material choice is only one factor in the overall price of ridge work. Length, access and the way the tiles are fixed usually count for more, which is why a figure is given only after the roof has been measured.
How replacements are matched
Matching begins with measurement. We note the length of each tile, the width across the base, the radius or angle, the thickness and the type of joint. We also record the colour, the finish and any markings stamped into the underside, which sometimes identify the maker. A photograph of a sound tile in good light, taken from the side as well as the top, helps a great deal if you are sending us pictures before the visit. If a tile has already come down and is lying in the garden, keep it and keep the pieces: a broken tile still gives us the profile, the colour and the maker's stamp, and it is worth far more as a sample than as rubbish. Do not climb up to look for the others.
With the profile known, the next step is to find the tile. We check what is still made in that pattern, then look at salvaged stock, then at the nearest alternative. For a single tile on a modern roof, a new one in the same range is usually straightforward. For older roofs, we prefer a reclaimed tile whose weathering already matches, because a new tile on an aged run will stay a different colour for a long time.
Next comes the fixing. Whatever the tile, BS 5534:2014 expects a ridge tile to be held by more than its mortar bed, so each one also gets a mechanical fixing. If the house is listed, or stands in a conservation area, the fixing should be as discreet as the tile, which is one reason a ventilated dry system is sometimes chosen where the loft needs the air; see our guide to the ventilated dry ridge for how that works.
Finally there is the edge. Where a ridge meets a verge, the edge that runs up the gable end, the end tile is shaped to cap it, and the verge itself may be held with clips; our page on verge clips explains that detail. After a storm, the first tiles to go are usually at the ends, a pattern we describe in our guide to wind and storm damage. The whole service sits under ridge and verge repairs.