Recessed covers allow paving to be laid within the tray maintaining the continuity of the paved surface whilst still allowing easy access to the underlying services. Where an existing manhole cover has straight sides, Plaspave can be laid in a stretcher course and butted up against the unit. Where this is not possible, it will be necessary to cut blocks as shown. Blocks can be laid on sand immediately next to the ironwork but should be mortared into position if there is a possibility of the sand migrating beneath the manhole surround. Also, if a manhole cover is used which will not allow the paving to abut the frame, then a surround of concrete with a cube crushing strength of 40N/mm2 must be constructed as shown.