Laying Guide for Setts & Cobbles
Setts and cobblestones may be laid directly on a layer of mortar; there should be no need to provide a hardcore sub-base in light-use areas such as paths. Use a fairly stiff cement-based bedding mix (10 parts sharp sand with 1 part cement) and spread to a thickness of at least 5 cm; preferably 7.5 cm.
Cobbles should be pushed into the bedding mix to at least half their depth. To create a surface suitable for walking on, lay the stones with their flattest side uppermost, and make sure that they are as close together as possible. However, if you are laying cobbles to create 'deterrent' paving, position them so that they stand vertically upwards and are spaced at least 1-2 cobbles apart. Make sure that they are firmly embedded (at least three quarters deep).
Finish off the joints by smoothing off the bedding matrix. This can be done a few hours after laying by sweeping with a soft brush and then washing down with a watering can fitted with a fine rose.
Deterrent paving should then be pointed with a strong mortar mix (1 part cement to 3 parts sharp sand) and then smoothed using a dowel or other round-ended tool. Black dyes may be added to the mortar to produce a more appealing look.
You should avoid walking on any newly laid cobbled or sett paving for at least 48 hours.
Whilst some setts are regular in size, others, especially reclaimed setts, can vary greatly. This may affect the size of the joints between each unit. Try to keep the distance between each one to less than 2.5 cm; if you find that you have any gaps larger than that, you should remove that sett and replace it with one that fits more snugly. Try to ensure that longitudinal joints on subsequent courses are staggered as this will provide a firmer, more stable surface.
Once the setts have been laid, fill in the joints to about one-third of their depth with the bedding mix. Tamp this down firmly and then water in with a watering can and rose. Care must be taken to ensure that none of the mix remains on the surface of the setts, otherwise they will become stained.
Finally, point the setts with a high strength mortar (1 part cement to 3 parts sharp sand plus a strengthening additive), preferably dyed black. Pack the mortar in between each joint, carefully clearing away any spillages. Smooth out the mortar between each sett.