Tile Length: 486mm. Tile Width: 296mm. Low-pitch vent tiles are also available for 17 to 15 degrees All tiles, fittings & accessories should be installed in accordance with the recommendations given in BS 5534: the British Standard Code of Practice for slating & tiling. Sitework should be carried out in accordance with BS 8000-6: the British Standard for workmanship on building sites. Contact Crest for technical support including estimates and fixing specification.