Half-round, angled and hogback ridge tiles

The half-round is the simplest profile: a smooth semicircular arch that laps over the next tile along the ridge. It is common on concrete and clay roofs of many ages, in plain clay colours and in the grey of concrete, and it suits both plain tiles and interlocking tiles.

Half-round tiles are usually bedded on mortar or carried on a dry-fix batten, and many still sit on old beds with only a thin, crumbling layer holding them. Their curve sheds water easily, and the arch gives a soft line along the top of the roof. They are also the easiest to find as a replacement, which is why many repairs on mixed roofs end up with half-round tiles whatever was there originally. A mismatch is more visible than people expect when the original tiles are glazed or hand made.

Unsure which you have? Look at the tile where the ridge ends at a gable: a half-round tile shows a clean semicircular outline, an angled one a pointed roof shape, and a hogback a hump.

An angled ridge is shaped like an upturned V with a flat face on each side. Angles vary, with the common ones for steeper and shallower pitches, so the tile has to match the roof's slope. A 90 degree angle suits a steep pitch, while a wider angle suits a lower one.

The profile is crisp. This shape is popular on slate roofs, on clay tiled roofs with a traditional look and on new-build roofs with concrete tiles that want a sharp line. Because the faces are flat, mortar bedding sits differently, and the joint between tiles needs careful finishing so water cannot track behind it. Angled ridges are also standard for dry-fix kits, many of which come with a matching angled profile.

Where the angle is wrong, the tile sits on its edges and rocks, which leaves gaps and cracked mortar. Getting the angle right is the main skill in selecting this profile. A tile that is too steep for the pitch lifts at its lower edges, and one that is too shallow leaves a gap along the crown where wind-driven rain can enter.

A hogback tile is arched across its width and also humped along its length, so each one rises toward the middle and falls at the ends, like the back of a hog. The ridge then reads as a row of gentle bumps. You see it on Victorian and Edwardian roofs, in terracotta and red clay, and often with decorative finials at the ends.

Gothic, ornamental and crested ridge tiles belong to the same family. They are cast or pressed in clay with a pattern along the top, and they carry weight and character. Replacing a cracked tile means finding a close match in colour, size and pattern, often from a reclamation yard or a specialist maker, and that search can take longer than the fitting. When no match turns up, a new tile in a similar clay is the next best, and the difference tends to soften as weather works on it.

These tiles are heavier than the plain profiles, and the old bedding underneath is usually lime-based. On a period house, that mortar choice is part of what keeps the ridge sound. Our guide to lime-bedded ridges on period and listed roofs explains why, and it matters most on protected buildings.

Not every roof wears a clay or concrete ridge. Cotswold District Council's 2000 guidance describes traditional stone ridges as simple angled sections of dressed stone, which a stone roof around Stroud may still carry. Slate roofs often finish with a clay angled ridge, a lead roll or a dry-fix angled kit, and fibre-cement slate roofs commonly take a ridge in a matching manufactured profile.

Lead rolls sit over a timber core and give a clean line on a slate roof, though they are a different trade skill. Our answer on whether a dry ridge can go on a slate roof compares the options for slate in more detail.

The point is that the ridge belongs to the roof's covering. Putting a modern concrete half-round on a stone roof changes its appearance, and on a listed or protected house it may need consent.

Four things decide the right tile: the covering it sits on, the pitch, the age and style of the building, and how it will be fixed. A like-for-like match is usually the best answer. On a modern roof of concrete interlocking tiles, the manufacturer's own ridge range is the natural choice. On an older clay roof, the best match is a tile with the same colour, glaze or texture, and a colour sample or a broken piece helps.

For measuring, note the angle or arch, the length and width of one tile, and whether the ends have a socket or a plain butt. Photographs of the ridge from the ground, plus a close view of any piece that has fallen, let us pick the nearest profile before a visit.

Fixing matters as much as shape. Whatever the profile, BS 5534:2014 expects a mechanical fixing in addition to the bed, because mortar's own grip cannot be relied on. The verge undercloak is a related detail at the gable end of the same roof.

Our written quote covers the tiles, fixings, bedding and access, and a 10-year workmanship guarantee in writing backs the work. Phone 01453 933613 with your pictures, or see the hub page on ridge, verge and dry-fix repairs.