Ridge Tile Calculator — How Many Ridge Tiles Do I Need?

Standard half-round, angular and universal ridge tiles are 450mm long. Laid end to end with a small lap, they cover about 0.45m each, so you need roughly 2.2 to 2.3 ridge tiles per linear metre of ridge or hip. (Traditional 300mm clay ridges cover 0.3m each, giving about 3.3 per metre — set the Effective Cover to 0.3m in Advanced Options for those.) Always round up and add about 5% wastage for breakages. For the main roof tiles, use our Roof Tile Calculator.

BS 5534:2014 (the British Standard code of practice for slating and tiling, mandatory after a transition period from March 2015) requires all ridge and hip tiles to be mechanically fixed — mortar alone can no longer be the sole fixing. Dry ridge systems are now the usual choice for new builds and re-roofs as they meet this requirement and resist wind uplift without relying on mortar. Mortar bedding is still used, but it must be combined with mechanical fixing (for example a clamp or screw to every tile).

A dry ridge kit typically includes ridge tree bars (batten straps), unions to join the bars, roll-out ridge sealing strips and clips. Each kit covers approximately 6 metres of ridge. Brands like Manthorpe, Klober and Marley all produce compatible systems. They attach mechanically to the batten, providing a secure fixing without mortar.

There is no published manufacturer rate for ridge-bedding mortar, so this is a practical rule of thumb only: allow roughly one 25kg bag of sand and cement per 3-5 linear metres of ridge (this calculator uses 4m as a starting estimate), using a 1:3 cement to sharp sand mix. Actual usage varies with the tile profile and how deep the bed is. Remember that under BS 5534:2014 mortar can no longer be the sole fixing — bedded ridge tiles must also be mechanically fixed, which is why most roofers now use a dry ridge system.

Hip tiles are often the same profile as ridge tiles (half-round or angular), but the hip end usually requires a special hip iron or hip end cap. Some systems use mono-pitch or bonnet hip tiles instead. Check with the tile manufacturer for the correct hip accessories for your specific tile range. Use our Hip Tile Calculator to work out hip tile quantities.