Lay a path, up the lawn, using Raj green sandstone slabs, to my shed.

Hi Stewart, You shouldn’t need a concrete slab underneath this for normal pedestrian use, provided the ground is reasonably firm and each individual slab is properly prepared and supported. If I were installing these as stepping stones through the lawn, I would mark the position of each slab first and excavate each area sufficiently to accommodate approximately 75–100mm of compacted MOT Type 1, followed by approximately 30–40mm of mortar, plus the thickness of the sandstone. The finished slabs can then be set at, or very slightly above, the surrounding lawn level so that water doesn’t sit on them and they don’t become a trip hazard. Compact the sub-base thoroughly. I would then lay each sandstone slab on a full bed of mortar, typically around 4:1 sharp sand and cement, rather than using five spots/dabs of mortar. A full bed gives the thinner sandstone continuous support and greatly reduces the likelihood of rocking, cracking or movement. I would also clean the underside of the sandstone and apply a suitable slurry primer/bonding slurry over the complete underside immediately before laying. This provides a much better bond between the natural stone and mortar. Tap each slab carefully into position with a rubber mallet and check it is fully supported with no rocking. If you’re cutting the sandstone, use a suitable diamond blade and take the appropriate precautions for silica dust. So, in short, a concrete base shouldn’t normally be necessary for what you’ve described. A properly compacted Type 1 sub-base, full mortar bed and primed sandstone would be the method I would recommend. Hope that helps. DK Services (Cheltenham) Limited

Hi Stewart, for this type of path you shouldn’t need a full concrete base, especially as it’s only for foot traffic. I’d dig out and prepare underneath each slab properly, use a compacted sub-base and lay the Raj Green slabs on a full mortar bed. This will keep them solid and stop them sinking or moving over time. Stepping stones would work really well through the lawn and can be finished level with the grass for a clean look. Thanks, Alex NSG Driveways

Your slabs are probably 20mm think, so I would dig out soil to about 150-160mm , place terram ( usually black rattan material) spread around 100mm of hardcore ( to save costs use recycled aggregate - just ask supplier) and 40mm of 5-1 mix sand-cement. Lay slabs on full bed. Point up .

For stepping stones with foot traffic only, you shouldn’t need a concrete base. I’d dig out each slab area, put down a compacted MOT Type 1 sub-base, then lay the sandstone on a full bed of mortar. Avoid just using spots of mortar, especially with thinner sandstone slabs. That should give you a solid job without overdoing it.