Will it fit? Planning and electrics check
Before you get quotes, check the three things that most often stop a garden sauna or cold plunge install: planning permission, the electrical supply, and whether the thing can physically get to the spot. This is general guidance for England and Wales — your local planning authority and a registered electrician are the authorities.
What are you installing?
Where the rules come from
Most garden saunas fall under permitted development as an outbuilding, subject to conditions on height, position and how much of the garden is covered — see the government guidance on planning permission in England and Wales and the Planning Portal. Those rights are removed or restricted for flats and maisonettes, listed buildings, and in many conservation areas and Article 4 areas.
Any new fixed electrical circuit is notifiable work under Part P of the Building Regulations. That means a registered electrician and a certificate — which a buyer's solicitor will ask for.
Scotland, Wales and Northern Ireland have their own planning and building rules, and this check is written against the England and Wales position.
Common questions
Do I need planning permission for a garden sauna?
Usually not. A garden sauna normally counts as an outbuilding under permitted development if it is single storey, no more than 2.5 m to the eaves, no more than 4 m overall (3 m if not dual-pitched), not forward of the principal elevation, and covers no more than half the land around the original house. If it is within 2 m of a boundary the whole thing must be under 2.5 m high.
Do I need planning permission for a cold plunge?
A free-standing garden plunge tub is normally treated like any other piece of garden equipment and does not need permission. It becomes a planning question when you build an enclosure around it, sink it into the ground with significant excavation, or the property is listed or in a conservation area.
Can I run a sauna or chiller from an extension lead?
No — not as a permanent arrangement. A sauna heater or plunge chiller outdoors needs a fixed, RCD-protected circuit installed by a registered electrician, in weatherproof enclosures, with the cable run appropriately. Extension leads through a window are a fire and shock risk and will not be accepted as compliant.