Do you need planning permission for a garden sauna?

The short version: in England, most garden saunas can be installed without a planning application, because garden buildings fall under permitted development. The condition that most often catches people is height near a fence: within two metres of any boundary, the whole building must stay under 2.5 metres. Wood fired saunas then carry a separate set of rules that have nothing to do with planning, and electric ones swap the flue for the fuse board. All of it is below, with the sources linked.

The permitted development limits that matter

Garden buildings, which is what a sauna cabin is in planning terms, are permitted development in England provided they stay inside these limits, taken from the Planning Portal's guidance on outbuildings:

Limit	The rule
Eaves height	Maximum 2.5 metres
Overall height	Maximum 4 metres with a dual pitched roof, 3 metres for any other roof
Within 2 metres of a boundary	Maximum overall height 2.5 metres
Garden coverage	No more than half the land around the original house may be covered by additions or other buildings
Position	Nothing forward of the principal elevation of the house

These rights attach to houses. If you live in a flat or maisonette, or you rent, the position is different and a conversation with the council or your landlord comes first.

The rule that actually catches people

A garden sauna usually goes at the bottom of the garden, against a fence, because that is where the space is. That puts it within two metres of a boundary, where the limit is 2.5 metres overall, not the 3 or 4 metres allowed elsewhere in the garden.

Plenty of barrel saunas and apex-roofed cabins clear 2.5 metres comfortably. A cabin that is fine in the middle of the lawn can need a planning application two metres to the left. So before you fall for a particular model, do two measurements: the height of the building including its roof, and the distance from where you want it to the nearest boundary. Those two numbers decide whether your purchase is paperwork-free.

When you do need permission

• Listed buildings: any outbuilding within the curtilage of a listed building needs planning permission.
• Designated land (conservation areas, National Parks, the Broads, Areas of Outstanding Natural Beauty, World Heritage Sites): a building at the side of the house needs permission, and more than 20 metres from the house the outbuilding is limited to 10 square metres.
• Over the height limits, or forward of the front of the house, or past half the garden covered: permission needed.

This article describes the rules for England. Wales, Scotland and Northern Ireland have their own versions, and they differ in the details, so check with your local authority if you are outside England.

Wood fired saunas carry rules that are not planning at all

Passing permitted development is not the end of the paperwork for a stove and flue. Four separate regimes apply, and retailers rarely mention them:

• Smoke control areas. Much of urban Britain is a smoke control area, and the government's own guidance says a chimney on the roof of a building is covered, giving a summerhouse as its example. Burning unauthorised fuel or emitting chimney smoke can bring penalties of up to £300 for smoke and up to £1,000 for buying unauthorised fuel, unless the appliance is on the Defra exempt list. Check your council's smoke control map before ordering a wood fired sauna, not after.
• Carbon monoxide alarm. Installing a fixed solid fuel appliance requires a CO alarm to BS EN 50291 in the same room, positioned on the ceiling at least 300 mm from any wall, or high on a wall, and between 1 and 3 metres horizontally from the appliance. Approved Document J, in force since 1 October 2022.
• Fuel. Wood sold in England in volumes under two cubic metres must be certified to 20 per cent moisture or less and carry the Ready to Burn mark. That is law, not advice.
• Sweeping. HETAS guidance is to sweep at least twice a year when burning wood, timed around the heating season.

Electric saunas swap the flue for the fuse board

An electric sauna avoids all of the solid fuel rules above. It does not avoid paperwork, and it is worth being straight about that.

The arithmetic first: a 6 kW heater at 230 volts draws about 26 amps, which is far beyond what a standard 13 amp plug and socket can carry. So a typical sauna heater needs its own dedicated, hard-wired circuit.

Under Approved Document P, a room containing a sauna heater is a special location, which means not just new circuits but any addition or alteration to existing circuits in that room is notifiable building work. In practice: a registered electrician does the work and issues an Electrical Installation Certificate or Minor Works Certificate plus a Building Regulations Compliance Certificate. Electrical Safety First puts the consequence plainly: homeowners must be able to prove electrical work meets Part P or they are committing a criminal offence, and councils can require non-compliant work to be altered or removed.

So neither route is form-free. The wood fired route brings the smoke and fuel regime; the electric route brings a notifiable electrical installation. Which one suits you is a different question, and our guide to wood fired versus electric takes it on properly.

Before you order

• Measure the overall height of the model you want, including the roof, and the distance from its intended spot to the nearest boundary. Two metres and 2.5 metres are the numbers to hold in your head.
• Check whether you are in a smoke control area on your council's website if you are considering wood fired.
• If your house is listed or you are on designated land, talk to the planning department before ordering anything.
• Budget for a registered electrician if the sauna is electric, and ask for the certificates by name.
• Think about how the building arrives as well as where it stands: our piece on access, ground and the day the lorry arrives covers the part of the purchase most people discover too late.

If you are still at the stage of working out what fits your garden at all, start with our outdoor sauna buying guide, check the footprint against Plan your space, and the cabins themselves are under outdoor saunas.

Sources

• Permitted development limits for outbuildings: Planning Portal. planningportal.co.uk
• Smoke control area rules and penalties: GOV.UK. gov.uk/smoke-control-area-rules, exempt appliances at smokecontrol.defra.gov.uk
• Carbon monoxide alarms: Approved Document J, 2010 edition incorporating the 2022 amendments. gov.uk
• Wood fuel moisture and Ready to Burn: GOV.UK. gov.uk
• Chimney sweeping frequency: HETAS. hetas.co.uk
• Notifiable electrical work and special locations: Approved Document P, 2013 edition. gov.uk
• Part P certificates and consequences: Electrical Safety First. electricalsafetyfirst.org.uk