Hip Tile Calculator — Tiles, Irons & Mortar

Hip length is derived from the roof span and pitch. For a standard hipped roof, each hip runs diagonally from an eaves corner to the ridge end. For an equal-pitch hip the formula is: hip length = √(half-span² + half-span² + rise²), where rise = half-span × tan(pitch).

It depends on the tile. Angular and half-round hip tiles are 450mm (clay) / 457mm (concrete) ridge-pattern tiles bedded down the hip — strictly about 2.3 per metre (≈430mm effective cover with a 5% lap), though this calculator uses a slightly more conservative 3 per metre (angular) and 2.8 per metre (half-round) to allow extra lap, cuts and waste. Bonnet hips are small lapped plain-tile units laid at 9.5 per linear metre (BMI Redland Rosemary clay/concrete bonnet datasheet). A 10% wastage allowance is added on top.

A hip iron is a single galvanised or stainless steel hook fixed at the foot (bottom) of each hip. It anchors the lowest hip tile and stops the whole hip course sliding down the slope, so you need one per hip — four for a standard hipped roof. This is separate from the per-tile mechanical fixings: BS 5534:2014 requires every ridge and hip tile to be mechanically fixed with a screw or clip even when mortar-bedded, which this calculator counts as roughly one fixing per hip tile.

Bonnet hip tiles are a specific style that overlaps the main roof tiles at the hip junction. They give a traditional appearance and are commonly used with plain clay tiles. If you choose bonnet tiles, this calculator accounts for the higher tile count. Use our Roof Tile Calculator to estimate your main tile quantities and our Ridge Tile Calculator for the ridge.

As a typical trade allowance, budget roughly 1.5kg of mortar per hip tile for bedding and pointing, mixed about 1:3 cement:sand (a common bedding-mortar guideline rather than a fixed datasheet figure). Actual use varies with bed thickness, tile profile and how much is pointed, so treat the result as a guide and follow the tile manufacturer's bedding guidance. Note that under BS 5534 mortar bedding alone is not sufficient — every hip tile must also be mechanically fixed.