Short answer: most garden saunas in England don't need a planning application, because they count as outbuildings under permitted development. That's only true if the sauna meets the limits below. Different rules apply in Wales, Scotland and Northern Ireland, and to listed buildings, flats and designated land.
Permitted development limits for outbuildings
A garden sauna is usually treated as an outbuilding. Under permitted development it must meet all of these:
| Rule | Limit |
|---|---|
| Near a boundary | No more than 2.5 metres high if it's within 2 metres of a boundary |
| Elsewhere in the garden | Eaves no higher than 2.5 metres; overall height no more than 4 metres with a dual-pitched roof or 3 metres with any other roof |
| Position | Not in front of the wall forming the principal elevation, which is usually the front of the house |
| Garden coverage | Outbuildings and extensions together cover no more than half the land around the original house |
| Storeys | Single storey only |
| Platforms | No verandas or balconies; any raised platform no higher than 0.3 metres |
Most barrel and cabin saunas are well under 2.5 metres tall, so the height rule rarely bites, but check the product page if you want it close to a fence.
When you're more likely to need permission
- Listed buildings: any outbuilding within the curtilage of a listed building needs planning permission.
- Flats and maisonettes: outbuilding permitted development rights don't apply. The same goes for houses created through certain change-of-use permitted development rights.
- Designated land (conservation areas, National Parks, the Broads, National Landscapes, formerly AONBs, and World Heritage Sites):
- outbuildings at the side of the house need planning permission;
- in National Parks, the Broads, National Landscapes and World Heritage Sites, buildings, enclosures, containers and pools more than 20 metres from the house are limited to 10 square metres in total.
- Article 4 directions: some councils remove permitted development rights in particular areas. Your council can tell you.
Getting certainty
If you want written confirmation, you can apply to your council for a Lawful Development Certificate for a proposed development. It isn't compulsory, but it's useful if you're close to a limit or plan to sell the house. Check the fee with your council.
Also check your deeds and any lease. Restrictive covenants on some estates need consent for garden buildings, and these sit outside planning law.
Building regulations
Planning and building regulations are separate. A detached garden building normally doesn't need building regulations approval if it has no sleeping accommodation and:
- it's under 15 square metres of floor area; or
- it's 15–30 square metres and is either at least 1 metre from any boundary or built substantially of non-combustible materials.
Two things still apply whatever the building's size:
- Electrics: a new circuit for a sauna heater, or a new outdoor supply, is notifiable electrical work under Part P. Use a registered electrician, who will self-certify it, or get building control sign-off. Sauna rooms have their own section in the wiring regulations (BS 7671, section 703). Our electrics guide explains more.
- Wood-fired stoves: follow the manufacturer's flue and clearance instructions. In a smoke control area you may only burn authorised fuels or use an exempt appliance, so ask your council.
Wales, Scotland and Northern Ireland
The broad idea is similar, but the limits and exceptions differ. Check with your local planning authority, or on Planning Portal (Wales), mygov.scot (Scotland) or nidirect (Northern Ireland) before ordering.
FAQs
Does a sauna count as an outbuilding?
Usually, yes. A garden sauna "for purposes incidental to the enjoyment of the house" is treated like a summerhouse or garden room. If you plan to run it as a business, for example renting sessions, different planning rules apply.
Can I put a sauna right against my fence?
Under permitted development, yes, if it's no more than 2.5 metres high. For building regulations, a building of 15–30 square metres within 1 metre of a boundary needs to be built substantially of non-combustible materials. Leave the manufacturer's clearances for ventilation, maintenance and any flue.
I'm in a conservation area. Can I still have a sauna?
Often, yes, in the rear garden, within the limits. Outbuildings at the side of the house need permission on designated land. Ask your council if you're unsure.
Can Birch & Berg confirm whether my sauna needs permission?
We can't confirm planning status for a specific property. We do list exact external dimensions and heights on every product page, so you or your council can check quickly.
General guidance for England, checked against the Planning Portal on 24 September 2026. It isn't legal advice. Planning rules can change, and your council has the final say.
Sources
- Planning Portal, outbuildings (planning permission): https://www.planningportal.co.uk/permission/common-projects/outbuildings/planning-permission
- Planning Portal, outbuildings (building regulations): https://www.planningportal.co.uk/permission/common-projects/outbuildings/is-building-regulations-approval-needed-for-an-outbuilding/
- UK Government, permitted development technical guidance: https://www.gov.uk/government/publications/permitted-development-rights-for-householders-technical-guidance
- UK Government, Lawful Development Certificates: https://www.gov.uk/guidance/lawful-development-certificates
- UK Government, Approved Document P: https://www.gov.uk/government/publications/electrical-safety-approved-document-p
- UK Government, smoke control areas: https://www.gov.uk/smoke-control-area-rules