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How to build a shed base (and which type to choose)
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My Shed Plans
Plans that include base and floor details alongside the shed itself, according to the vendor.
Which base should you choose?
| Base | Best for | Effort |
|---|---|---|
| Concrete slab (75–100 mm on hardcore) | Workshops, heavy machines | High |
| Paving slabs on MOT Type 1 | Sheds up to ~8×10 | Medium |
| Timber frame on blocks/ground screws | Sloping or soft ground, fast builds | Low |
| Plastic grid base | Light sheds on level ground | Low |
Step by step: paving slab base
- Mark out 5–10 cm larger than the shed on each side with pegs and string; check diagonals match.
- Dig out 10–15 cm of turf and soil.
- Add compacted sub-base (e.g. MOT Type 1) in two layers, tamping each.
- Lay slabs on a sand/cement mix, checking level in both directions.
- Leave a slight fall (about 1:100) away from the door if you want water to run off.
My Shed Plans
Plans that include base and floor details alongside the shed itself, according to the vendor.
Step by step: timber frame base
- Set concrete blocks or ground screws at each corner and every ~1.2 m.
- Lay pressure-treated bearers (rated for ground contact) and level with packers.
- Fix joists at 400 mm centres; square by measuring diagonals.
- Keep timber off the soil and allow airflow underneath.
Common mistakes
- Base the same size as the shed, so rain drips onto it and wicks into the floor.
- Skipping the sub-base on clay soils.
- Untreated timber touching the ground.
Next: the full shed build.
Common questions
Do I need a concrete base for a shed?
No. Paving slabs or a treated timber frame are fine for most garden sheds; concrete suits heavy workshops.
How thick should a concrete shed base be?
About 75–100 mm of concrete over 75–100 mm of compacted hardcore is typical for a garden shed.
Can I put a shed directly on grass?
It isn’t recommended. The floor will rot and the shed will go out of level.
What we’d look at next
My Shed Plans
Plans that include base and floor details alongside the shed itself, according to the vendor.
TedsWoodworking
A large plan library that includes outdoor builds and sheds.
Not sure which fits? Take the 30-second quiz or see our comparisons.
Related comparisons: TedsWoodworking vs My Shed Plans · Best woodworking guides for beginners: 3 compared
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