Concrete shed bases: a practical guide.

A concrete base gives a shed, summerhouse or garden room a level, durable foundation. This guide covers the basics of planning a base and ordering the right amount of concrete. For larger garden buildings or anything with building regulations requirements, follow the manufacturer's or designer's specification.

Size and depth

Make the base the same size as the building footprint or slightly larger, as advised by the building manufacturer. A depth of around 100 mm of concrete over a compacted sub-base is commonly used for typical garden sheds; heavier buildings, workshops or vehicle use need a design specific to the load.

How much concrete do I need?

Length × width × depth in metres. Examples:

• 2.4 m × 1.8 m × 0.1 m = 0.43 m³
• 3 m × 2.4 m × 0.1 m = 0.72 m³
• 4 m × 3 m × 0.1 m = 1.20 m³
• 5 m × 4 m × 0.1 m = 2.00 m³

Add an allowance for uneven ground – our volume calculator adds 10%.

Preparing the ground

1. Mark out the base and remove turf and topsoil.
2. Dig down to allow for the sub-base and concrete depth.
3. Lay and compact a hardcore sub-base.
4. Set timber formwork level and secure, allowing a slight fall if needed.
5. Optionally lay a membrane over the sub-base.

Which concrete mix?

Tell us the job is a shed base and we will advise on a suitable mix.

Ordering a small load

Shed bases are often small volumes. Minimum loads, part loads, vehicle sizes, charges and delivery times are confirmed when we quote your job – ring 01302 238340 or use the contact form. If the base is in a rear garden, measure the route from the road; barrowing or pumping may be needed. Have helpers, barrows, a tamping board and a float ready before the vehicle arrives. See domestic concrete and our concrete cost guide.

Frequently asked questions