The short answer
A mitred hip is a hip finished by cutting the slates on both slopes at an angle so their edges meet along the hip line, with lead soakers underneath to carry water across the join. There are no hip tiles on top, so the line looks sharp and flush. It is a neat, traditional finish, but it demands skilled cutting and careful lead work, and it is not the cheapest option.
Where hips come from and what they do
A hip is the sloping ridge that runs from the main ridge down to the eaves at the end of a hipped roof, where two slopes meet at an external angle. Every hip is a place where water from both slopes must be directed down and off the roof. The slates on each side stop at the line of the hip and need something to seal the join. The common answers are a row of hip tiles bedded or clipped on top, a lead roll, or a mitre, where the slates themselves form the finish.
Because the hip runs diagonally, the slates can't simply stop square. Each one has to be cut to the angle of the hip, so the edge follows the line and the courses on either side match across the join. That diagonal cutting is the origin of the word mitre, borrowed from joinery.
How a mitred hip is built
The roofer works from the eaves up. A hip iron, a metal bracket fixed at the foot of the hip, supports the weight of the finish so it cannot slide. As each course of slate is laid, the last slate on each side is cut at the hip angle, its edge ground or cut so it meets its partner closely. Under each pair goes a lead soaker, a rectangular piece of lead bent to a shallow angle, which carries any water that gets through the joint onto the slate below and away. The soakers are cut to the gauge of the slates so each overlaps the one beneath, working up the hip like scales.
The slates themselves are fixed with nails or hooks, and, in line with current standards, the hip should be mechanically fixed and not relied on to stay put by friction or bedding alone. The standard for slating, BS 5534, expects hips to be held by mechanical fixings. Our page on ridge options for slate roofs covers the top of the roof, which meets the hip.
Why choose a mitred hip
The appeal is appearance. A mitred hip shows slate all the way along, with a thin, crisp line instead of a row of thick capping, and it suits formal buildings, period houses and roofs where the owner wants the slope to read as a single plane of stone. It has no mortar to crack and no joints between hip tiles to leak. Done properly, it can last as long as the slates around it.
The costs are skill and time. Every slate on the hip is cut by hand, and a poorly cut mitre leaves gaps that let water and wind in. The lead soakers need to be right. It is a job for someone with slate experience, not a general tiler. If the hips are damaged, repairs are fiddly, because replacing one slate in a mitre means disturbing its neighbours and the soakers behind.
Mitred hips compared with alternatives
Hip tiles, whether clay or concrete, are quicker, cheaper and more forgiving, and they can be fixed mechanically with clips or brackets. A lead-covered hip is neat and long-lasting but shows as a dark line. A bonnet hip uses curved, hooded tiles over the join. Each of these suits some roofs. On a roof that already has mitred hips, repairs should stay the same, unless the owner chooses a change, since altering the hips changes the character of the building. If it is listed, ask the council whether consent applies first.
You can spot a failing mitred hip from the ground by gaps between the slates along the line, slipped or missing slates, and lead showing where it should be hidden. In the loft, a damp stain below the hip line is another sign. The page on slipped and cracked slates describes the usual failures, and what a slate-and-a-half is covers another cut-slate detail.
Cost and who should build one
A mitred hip takes longer than a capped one because each slate along the line is measured, marked and cut, and the lead soakers are made to suit. Expect it to cost more per metre of hip than clip-on hip tiles, and to need a roofer who regularly works with slate. Ask to see photographs of previous mitred work, or ask how the hip iron, soakers and fixings will be handled. A good roofer will explain the sequence readily, and will be able to tell you what is hidden under the slates, because that is where the quality lies.
We look at hips in close-up photographs during a survey, so you can see the cut edges and the lead for yourself, and a repair is priced at a fixed sum. Our overall approach to this material is set out under slate roofing in Basingstoke.
Every roof is different. A free survey with photos settles it for yours.
Get a free survey