How to build a garden sandpit

Inspired by a helpful UK garden video. This guide draws on "How to Build a Sandpit" from the Wickes YouTube channel. The Wickes team run through a sleeper-built sandpit that is straightforward to follow and produces a genuinely solid result — much better than the flimsy plastic kits you see in catalogues. Worth watching if you want a visual run-through before picking up any timber.

1. Choose the right spot

Somewhere in partial shade is ideal. Full sun means the sand gets uncomfortably hot on warm days and dries out very quickly. Under a tree can sound appealing but you will spend a lot of time fishing out leaves, seeds, and other debris.

Flat, level ground makes the build far easier. Allow a generous margin around the pit itself — children do not confine themselves neatly to the inside of the frame, and you want room for kneeling adults too.

2. Mark out and excavate

A good size for a family sandpit is 1.5m × 1.5m, though anything from 1.2m to 2m works well. Mark the outline with pegs and string, then excavate to a depth of around 200–250mm. Remove the turf first if you are cutting into a lawn, and stack it elsewhere in case you want to relay it later.

Check the base is reasonably level — a difference of 20–30mm across the whole area is fine, but bigger variations will make the frame harder to sit evenly.

3. Lay a weed membrane

Line the excavation with a permeable weed-control membrane, cut to fit and tucked up the sides. This keeps weeds from growing up through the sand while allowing water to drain away freely. Secure the edges with staples or heavy stones while you work.

Do not use an impermeable liner — standing water in a sandpit is both a hygiene risk and a nuisance. Drainage is the point.

4. Build the timber frame

Railway sleepers give a chunky, attractive look and are extremely durable. Half-sleepers (cut lengthways) are easier to work with and less heavy. Alternatively, two layers of 100mm × 47mm decking board gives a good depth at lower cost.

Cut the timbers to length and stack them in a square frame, overlapping at the corners like log-cabin walls. Screw through the corners with 150mm structural screws. If using sleepers, pilot-drill first — they are dense and will split if you force a screw in without a hole.

5. Add corner posts if needed

For a multi-layer frame or a larger pit, drive short timber posts into the ground at each corner and fix the frame boards to them. This keeps everything square and stops the sides bowing outward under the weight of sand.

Use 75mm × 75mm pressure-treated posts. Cut them to sit just below the top of the frame so they do not create a snag for small hands.

6. Fill with play sand

Use kiln-dried play sand, not sharp sand or builder's sand. Play sand has been washed and graded specifically for children — it is the right texture, the right colour, and free from the particles that would irritate eyes and skin. You will need roughly 200–400kg for a standard-sized pit depending on how deep you want the sand.

Fill to about 150mm depth — enough to dig in but not so much that sand constantly spills over the sides.

7. Fit a cover

A cover is not optional — it keeps cats out overnight and stops rain turning the sand into a soggy mess. Cut a sheet of exterior plywood to the inside dimensions of the frame, with small rope handles at each corner for easy lifting. Alternatively, hinged lid boards that double as bench seats work nicely and make the pit feel like proper garden furniture.

Apply exterior wood stain or paint to any exposed timber — it genuinely extends the life of the project by several years in the British climate.

When to call a handyman

Call Richard if you want the job done quickly and properly, or if the ground is uneven and needs levelling first. A clean, well-built sandpit is a satisfying project, but it involves more lifting and ground preparation than it looks on paper.