How to lay a path with slabs

Video by Wickes. This walk-through is based on the video "How to lay a path with Wickes" from the Wickes YouTube channel, which covers gravel, slab, and block-paving path construction in a clear step-by-step format. The section on setting out and sub-base preparation is particularly worth watching before you start digging.

1. Plan the route and mark it out

Before you do anything else, walk the route a few times at different times of day. Where does the garden naturally want you to go? A path that follows the desire line people already use will get walked on; one that cuts across it will get ignored. Once you are happy with the line, knock in timber pegs at each end and run a string line between them. For a curved path, a garden hose laid on the ground is the easiest way to work out a pleasing arc.

Mark the edges with spray line marker or a trail of sand. Allow for the width of the slabs plus any edging you plan to use — most standard paving slabs are 450 mm or 600 mm square, so a single-file path will typically be 600 mm wide between edges. Measure twice; you do not want to order slabs and find they do not quite fill the width you have dug.

2. Excavate to the right depth

Dig out the path to a depth of around 150 mm to 200 mm below the finished surface level. That allows for roughly 100 mm of compacted sub-base (MOT Type 1 hardcore), a 40 mm mortar bed, and the slab thickness itself, which is usually 35 mm to 50 mm for standard concrete paving. Check your slab thickness before you dig — natural stone and porcelain can vary quite a bit.

Make sure the base of the trench slopes very slightly away from the house — a fall of around 1 in 60 (roughly 15 mm per metre) is enough to shed rainwater without it being noticeable underfoot. In East Kent gardens with heavy clay, decent drainage is not just a nicety; it is the difference between a path that stays solid and one that heaves after a cold winter.

3. Lay and compact the sub-base

Tip in your MOT Type 1 hardcore in two layers of around 50 mm each, compacting each layer with a vibrating plate compactor (hire one for the day — it is well worth it for a path longer than about 3 m). Raking it level before you compact keeps the finished surface consistent. If you use a hand tamper, give it a thorough going over; a poorly compacted sub-base will settle unevenly and the slabs will rock.

That said, for a short stepping-stone path through a border, a hand tamper and some patience will do the job. The key is getting the sub-base firm and even before you go any further. Lay a straight-edge across it to check for any high spots and knock them down before moving on.

4. Mix the mortar and set the first slabs

Mix your mortar at roughly four parts sharp sand to one part cement — it should be a firm, damp consistency, not sloppy. Lay enough mortar for one slab at a time so it does not start to set while you are fiddling with the next one. Apply it in five dabs (one in each corner and one in the centre) for smaller slabs, or as a full bed for larger ones. A full bed gives better long-term support and reduces the chance of slabs cracking underfoot.

Place the first slab at one end of the path and bed it down firmly with a rubber mallet. Check it is level across two directions and that it sits at the correct finished height. This first slab sets the reference for everything else, so take your time getting it right. You can pack a little extra mortar under any low corner — just do not be tempted to slide the slab around once it is down, as that breaks the mortar bond.

5. Work along the path and keep checking levels

Use tile spacers or off-cuts of timber to maintain consistent joint widths as you work down the path. Most people go for a joint of around 10 mm to 15 mm, which gives room to point neatly without being too wide. After every three or four slabs, lay a long spirit level or straight-edge across them to check they are sitting flush with each other and that the slight drainage fall is being maintained.

Cut any slabs that need to fit around edges or curves using an angle grinder with a diamond blade or a hired slab splitter. An angle grinder is faster but dusty — wear a dust mask and eye protection, and dampen the cut if you can. Mind you, for a simple straight-sided path you may not need to cut any slabs at all if you plan the layout beforehand.

6. Point the joints and finish the edges

Leave the mortar bed to cure for at least 24 hours before walking on the slabs or attempting to point. Mix up a slightly stiffer mortar (or use a ready-mixed pointing mortar) and press it firmly into the joints with a pointing trowel or a brick bolster. Smooth it off to a slightly recessed finish — this helps water run off rather than pooling. Remove any mortar smears from the slab faces with a damp sponge before they set.

For the path edges, haunching mortar up against the side of the outside slabs gives extra support and stops the edges rocking or dropping over time. Alternatively, fit proprietary plastic or steel edging before you lay the sub-base. It depends on the look you are after — metal edging looks clean and modern; haunched mortar suits a more traditional garden. Either way, protect the edges from foot traffic while the mortar cures for 48 hours.

When to call a handyman

Call Richard if the ground is very uneven, heavily compacted clay, or if there are buried pipes or drainage runs to work around. Laying a longer path single-handed is also slow going — handling full-size paving slabs safely really needs two people. If you want the path built in a day rather than across several weekends, or if the route involves awkward cuts, steps, or changes of level, it is worth getting someone in who has laid a few before.