Groundwork guide

How to prepare a shed base

Six steps, basic tools, one honest weekend — and the slab wants a good 48 hours to cure, so start well before your delivery slot.

Which base do I need?Delivery information

01 / 06

Step 1 of 6

Choose the Spot

Pick firm, well-drained ground — a slight slope is fine, a bank is not.
Leave at least 2ft clear on every side for building and future re-treating.
Walk the delivery route: the panels need a clear path from the kerb to the spot.

Don't push it tight against the fence — you'll thank yourself every time you treat the back wall.

2ft clear all round

Firm, level ground

Clear delivery access

Your kit

Pegs & string linemarking out
Tape measuresizes + diagonals
Spade & wheelbarrowturf and spoil
Hardcore (MOT Type 1)the sub-base
Timber for formworkholds the edges
Concretemixed on the stiff side
Spirit levelcheck both ways
Straight screed boardflattens the top

The six steps

1Choose the spotFirm, well-drained ground with at least 2ft of clearance on every side — and a clear route from the kerb for the delivery team.
2Mark out and square itPeg out the corners, run string between them and measure both diagonals — when they match, your base is square.
3Dig out and lay hardcoreStrip the turf, dig down about 150mm, then fill half the depth with hardcore (MOT Type 1) and compact it down hard.
4Fix formwork and pourFix level timber formwork around the edges, pour the concrete, work it into the corners and screed the top off flat.
5Check level and let it cureThe bubble should sit dead centre both ways. Leave the slab a good 48 hours, covered if rain is forecast, and slightly proud of ground level so water runs off.
6Ready for delivery dayThe base must be down, level and fully cured before your delivery slot — good access and a solid base mean your building goes up in hours.

Concrete isn't the only option

A concrete slab is the do-it-once answer, but paving slabs or a timber base suit plenty of gardens too. The written guide walks through what each option costs and when it's the right call.

Read the base guide

Base ready before the big day

Your base needs to be down, level and cured before the delivery slot — check lead times and what happens on the day.

Delivery information

Total Sheds

The six steps

1Choose the spotFirm, well-drained ground with at least 2ft of clearance on every side — and a clear route from the kerb for the delivery team.

2Mark out and square itPeg out the corners, run string between them and measure both diagonals — when they match, your base is square.

3Dig out and lay hardcoreStrip the turf, dig down about 150mm, then fill half the depth with hardcore (MOT Type 1) and compact it down hard.

4Fix formwork and pourFix level timber formwork around the edges, pour the concrete, work it into the corners and screed the top off flat.

5Check level and let it cureThe bubble should sit dead centre both ways. Leave the slab a good 48 hours, covered if rain is forecast, and slightly proud of ground level so water runs off.

6Ready for delivery dayThe base must be down, level and fully cured before your delivery slot — good access and a solid base mean your building goes up in hours.