Key facts
- Most common failure
- Uneven or undersized base
- Cheapest workable base
- Plastic grid on hardcore
- Best for heavy buildings
- Concrete slab
More sheds fail because of the base than because of the shed. A base that is uneven, too small or holds water will twist the frame, jam the door and rot the floor bearers.
| Base type | Suits | Notes |
|---|---|---|
| Paving slabs | Most timber sheds | Level, well-bedded slabs on sharp sand; easy to correct later |
| Concrete slab | Workshops, log cabins | Best for heavy buildings; needs formwork and curing time |
| Plastic grid | Small and mid sheds | Quick, permeable, laid on compacted hardcore |
| Timber frame | Sloping ground | Pressure-treated bearers on pads; keeps the floor ventilated |
Rules that apply to all bases
- The base should match the shed floor size, not overhang it, so rain runs off rather than pooling.
- Check level in both directions with a long spirit level before assembly starts.
- Keep the timber floor off wet ground — bearers or a damp-proof membrane are essential.
- Allow the base to settle or cure fully before building on it.
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