Please note this colour ridge is used with duoplain concrete roof tiles in the charcoal grey colour. Coverage Length: 450mm. Half round ridge They can be dry fixed, mortar bedded only or mortar bedded and mechanically fixed. When ridge tiles are mortar bedded & mechanically fixed, use Clamping Plates and woodscrews, complete with neoprene washers and foam grommets. A 6 mm diameter hole should be carefully drilled centrally in each ridge tile. A Block End Half Round Ridge Tile must be used at the verge when using the Cloaked Verge or Ambi-Dry Verge System. Capped Half Round Ridge Tiles are available for use with Cathedral Clay Pantiles and Old Hollow Clay Pantiles in Vintage Blue, Vintage Red, Terracotta and Brindle. If Rapid Vented Ridge is required when using Cathedral, use Rich Terracotta Half Round Ridge Tiles with Cathedral Terracotta and Terracotta Brindle Ridge Tiles with Cathedral Brindle. When using Old Hollow, Cathedral, Regent, Grovebury, Norfolk Pantile or Landmark Double Pantile with mortar bedded ridge tiles, bed Dentil Slips in the pans of the tiles.