How to Build a Concrete Shed Base (UK Thickness, Cost & Specs)

A properly built concrete shed base is the strongest and longest-lasting foundation for any garden building. In this guide, we explain exact thickness requirements, costs, UK building best practices, and when a concrete base is the right choice for your shed.

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When Do You Need a Concrete Shed Base?

A concrete base is recommended when installing:

Large or heavy garden buildings
Workshops or insulated garden rooms
Motorbike or security sheds
Sheds on sloped or soft ground

Explore suitable buildings here: Heavy Duty Sheds | Motorbike Sheds | Garden Rooms

Large wooden shed installed on a concrete base

Concrete Shed Base Thickness (UK Standards)

Shed Type	Recommended Concrete Thickness
Small sheds (6x4 – 8x6)	100mm (4 inches)
Medium sheds (10x8 – 12x8)	100–125mm
Large / Heavy-duty sheds	125–150mm + reinforcement

Tip: For heavy buildings, install A142 steel mesh within the concrete slab for strength and crack resistance.

Step-by-Step: How to Build a Concrete Shed Base

Mark out the area – allow 50–75mm extra on each side.
Excavate to around 150–200mm depth.
Add MOT Type 1 sub-base and compact thoroughly.
Build shuttering using timber boards.
Lay damp-proof membrane (DPM).
Pour concrete, level using a straightedge.
Allow to cure for at least 7 days (28 days ideal).

UK guidance on concrete strength and curing: Designing Buildings – Concrete

Large apex shed installed on a concrete base

Concrete Base Cost in the UK

Item	Typical Cost
Concrete (per m²)	£60 – £90
Ground preparation	£20 – £40 per m²
Labour (if hired)	£150 – £250 per day

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Best Sheds to Install on a Concrete Base

Concrete bases are ideal for heavier buildings such as:

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Frequently Asked Questions

How long should concrete cure before installing a shed?
Minimum 7 days, ideally 14–28 days for full strength.

Can I install a shed directly on concrete?
Yes, but we recommend pressure-treated bearers to improve airflow and prevent moisture transfer.

Is planning permission required?
Usually no, but check official guidance: Planning Portal

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Whether you're installing a small garden shed or a large workshop, the right base ensures decades of durability.

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