Start with a properly prepared slab or concrete base where the shed maker permits it. Our priority is a firm, level foundation that supports the whole building and accepts its anchors. Choose the shed first, so the base is built to the right specification; a flat-looking patch of lawn will not do the same job.
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Distinguish four different items
- Floor
- The surface inside the shed, where one is supplied.
- Bearers or base frame
- Components supporting the building as specified by its manufacturer.
- Foundation
- The prepared ground structure carrying the load.
- Anchoring
- The fixings and supporting material resisting movement, where required.
Check all four lines in the quote. “Base included” is too vague to budget from.
Compare options against a written specification
| Proposed option | What must be established |
|---|---|
| Concrete | Dimensions, ground preparation, level, drainage and anchor requirements |
| Paving slabs | Whether the exact building and its anchors permit them; support and settlement control |
| Timber system | Model compatibility, support points, treatment and permissible ground contact |
| Plastic grid system | Approved loading, infill, edge restraint and whether required anchors can be accommodated |
Keter recommends a flat, level surface and identifies timber or concrete foundations for its larger items. Asgard publishes model base sizes and treats optional ground-anchor installation separately from shed support. These examples demonstrate why one generic slab or concrete-depth recipe is insufficient. Keter preparation; Asgard installation.
Check the finished surface
For local level checks, we recommend the Stabila 70-2 60cm spirit level (2324), which has horizontal and vertical vials. A 60cm level checks only the section beneath it: use a suitable straightedge and check across the base in both directions, following the shed maker’s tolerances. Have the installer confirm the whole foundation is ready.
See the Stabila 70-2 60cm at Amazon (paid link)
Obtain the base drawing before booking work
Give the installer the manufacturer, exact model, footprint, maximum external dimensions, intended contents and anchor instructions. Ask for the finished level and treatment of surrounding surface water to be shown. If the site is sloping, unstable or persistently wet, have the ground conditions assessed rather than adapting an internet recipe.
Keep ground preparation, waste removal and carrying materials to the site as separate quote lines. Confirm who will check that the finished base is ready before the shed arrives.
Your next step
Sources and method
- Keter UK questions and care guidance · checked 2026-09-19
- Asgard installation service · checked 2026-09-19