Why the base matters
A garden room needs a level, stable, well-drained base to sit on — get this wrong and the most common results are doors that stick, floors that flex underfoot, or damp working its way up into the structure over time. It's one of the least visible parts of a garden room build, but it's also one of the most important for how the building performs for years to come.
Types of base
The three most common approaches are a poured concrete pad, a screw-pile foundation (steel piles driven into the ground with a supporting frame on top), or a paved or block base. Which one makes sense depends on your soil type, how level the plot already is, drainage, and how heavy the finished building will be.
Screw piles tend to suit sloping or uneven gardens well since they can be adjusted for level without major excavation, while a concrete pad is often preferred for larger or heavier buildings on reasonably flat, stable ground.
Site considerations that affect the base
Clay soil, a high water table, or a garden that slopes noticeably can all change what base is sensible and what it costs — this is exactly the kind of thing that's hard to judge without seeing the actual plot. Access for machinery and materials matters too, particularly on a garden reached only through a narrow side passage or over an existing patio.
Getting groundwork into your overall quote
If you're getting quotes for a full garden room, make sure the base and any groundwork are itemised separately rather than folded into one vague total — it's the part most likely to change once an installer has actually seen your garden. Ask what happens if unexpected ground conditions are found once digging starts, and get any variation to the price confirmed in writing before work continues.
Frequently asked questions
Do I need planning permission just for a base?+
A base on its own, without a building on top, doesn't generally need planning permission, but it's worth checking with Eastleigh Borough Council if you're doing significant groundwork or the site has any particular constraints.
How do I know if my garden needs a concrete base or screw piles?+
It depends on your soil, drainage and how level the plot is — an installer will usually be able to advise after seeing the site or reviewing photos, and should explain their reasoning as part of the written quote.
Can groundwork be done separately from the garden room build?+
In some cases yes, though most installers prefer to handle the base and the structure together so they can guarantee the fit between the two — worth asking directly when you get your quote.
Useful local links
- Winchester City Council – Do I Need Planning Permission — The planning authority covering Bishop's Waltham, Curbridge, Curdridge and Durley.
- Fareham Borough Council – Planning — The planning authority covering Swanwick, Lower Swanwick, Sarisbury Green and Burridge.
- Southampton City Council – Planning — The unitary planning authority covering the city of Southampton.
- Planning Portal – Outbuildings — National guidance on permitted development rules for garden buildings and outbuildings.