Dry Hip or Mortar Hip?

What a hip is

A hip is the sloping line where two roof slopes meet at an outward corner, running from the ridge down to the eaves. Hipped roofs have them on every corner, and the tiles that cover them are hip tiles. At the bottom end a hip tile can slide, so it is held by a hip iron, a small metal bracket screwed to the rafter. Our guide to hip tiles, hip irons and dry hip systems covers the parts in detail.

How a mortar hip is built

Traditional hips sit on a bed of mortar laid along the junction, with the cut tiles on each slope tucked underneath it. The mortar fills the gap, bonds the hip tiles and keeps the wind out. Done well, it looks neat, matches clay roofs and can last many years. The weakness is that mortar is rigid and the roof is not. Seasonal movement, frost and vibration crack the bed, water gets in, and tiles begin to loosen from the bottom up.

How a dry hip is built

A dry hip replaces the mortar with a batten or a ridge board, with the hip tiles clamped or screwed to it and a ventilated, flexible strip sealing the edges. Nothing relies on cement, so there is nothing to crack. The system comes with its own tiles or with fittings for the existing ones, and BS 8612:2018 sets the performance requirements for dry-fix products. BS 5534:2014 expects ridge, hip and verge parts to be fixed mechanically, which dry systems do by design.

The comparison

The comparison is not about one being right everywhere. A listed building or a conservation area may expect mortar and traditional detailing, and the council's conservation officer is the person to ask.

Cost and lifespan

A dry system usually costs more to put in, because the components are manufactured and the fitting is exact. Over time it may cost less, since there is less repointing. Reported dry ridge prices for a semi-detached house sit at roughly £900 to £1,600, a typical UK range, and hips are worked out in the same way. Your fixed quote follows the survey. Our page on dry ridge against mortar-bedded ridge makes the same comparison for the ridge itself.

What goes wrong with each

Mortar hips fail from the bottom, where the hip tile meets the eaves and the weight of the run bears down. Once the bed behind the lowest tile cracks, the tile creeps and pulls the next one with it. Dry hips fail differently: a clip that was not fully seated, a screw that has backed out or a batten that has rotted. These faults are easier to see and cheaper to correct, because the fix is a fixing, not a rebuilt bed. In both cases the hip iron at the base matters, and a rusted or missing iron is a common reason a hip starts to slip.

Which suits your roof

Choose by the roof you have, not by fashion. A modern concrete-tiled estate house with failing hips is a good candidate for a dry hip, since the profile is standard and the fittings are made for it. A handmade clay roof on an older house, where the hips are part of the character, may be better re-bedded in a lime-friendly mortar with proper mechanical fixing added. A roof that faces the prevailing south-westerly wind and sits on open ground puts more load on a hip, which favours a system that does not rely on a bond. If you are re-covering the whole roof and have not yet picked a finish for the corners, the choice is simple to make at the same time, and the hips are done once.

What we do

We look at the hips on the survey, photograph the bedding and tell you if they can be re-bedded and fixed or whether a dry hip makes more sense. Repair where repair works is our rule, so a sound hip that only needs pointing gets pointing, and you see the photos of the bedding before you decide on anything larger. Visit our ridge, verge and dry-fix page for the wider range of work.