A sauna is only as good as what it stands on and what powers it. Most problems on delivery day come from a base that isn’t level, a route that’s too tight, or electrics that weren’t planned. Here’s what to sort out first.
The base
Manufacturers ask for a firm, level surface such as paving, a concrete pad or sound decking, and for the sauna not to sit in standing water. In practice that means:
- Level: check it with a long spirit level in both directions. Doors and panels can bind on an uneven base.
- Big enough: at least the full footprint of the sauna. A little extra around the edge makes maintenance easier.
- Drained: avoid low spots where rain collects, and keep the base clear of soil and plants so air can move underneath.
- Strong enough: especially for cold plunge tubs. Water weighs about 1 kg per litre, so a 900-litre tub holds around 900 kg of water before you add the tub and the people in it. Ask your builder to confirm the base can take the load, particularly on decking.
Don’t book delivery or installation until the base is finished and, if it’s concrete, has had time to cure. Your builder can tell you how long that takes. Installers may ask for photos of it first.
The electrics
Treat this as a job for a qualified electrician, not a DIY task.
Hard-wired traditional heaters
Traditional electric sauna heaters are usually connected on a dedicated circuit. In England, the Building Regulations (Part P) make the installation of a new circuit notifiable work, as is any addition or alteration to existing circuits in a room containing a sauna heater. The work has to be certified, either by an electrician registered with a competent person scheme, through a registered third-party certifier, or by building control. You should receive a BS 7671 electrical installation certificate and a Building Regulations compliance certificate.
Plug-in models
Some infrared saunas and plunge chillers run from a standard 13 A socket. Outdoors, that socket should be weatherproof and RCD-protected, and an electrician should confirm it’s suitable for the load. Avoid extension leads.
Questions to give your electrician
- The heater’s power rating (kW) and the supply the manufacturer specifies.
- Distance from your consumer unit to the sauna.
- Whether your consumer unit has spare capacity for a new circuit.
- Where the isolator and any controller will be mounted.
Access and delivery
- Measure gates, side passages and doorways on the route, and note any steps or slopes.
- Saunas usually come as several large boxes. Some suppliers deliver with one driver and ask for a second adult to help unload.
- Remote areas, islands and addresses with difficult access may need a separate quote.
Installation
Depending on the model and supplier, you may be able to build the sauna yourself from the manual or have it assembled by the supplier’s team. Before an installation date is set, expect to be asked for photos or a short video of the route and the base. Where a retailer’s team assembles the sauna, the electrical connection is often left to your own electrician, so check what’s included.
Checklist
| Before you order | Before delivery |
|---|---|
| Spot chosen and measured, including overhangs Planning position checked Electrician has quoted Access route measured | Base finished, level and drained Supply installed or booked Route cleared Second adult available to help unload |
- Approved Document P: Electrical safety – dwellings, regulation 12(6A) and section 3 (certification procedures), assets.publishing.service.gov.uk.
- Retailer guidance on base, electrical supply, delivery and installation, outdoorliving365.co.uk product pages (read 3 November 2026).
- Planning Portal, “Outbuildings: planning permission”, planningportal.co.uk.
Rules quoted apply to England unless stated. Scotland, Wales and Northern Ireland have their own planning and building regulations. This guide is general information, not professional advice; check your own circumstances with your local authority and a qualified electrician.