Do you need planning permission for a garden sauna?

When a garden sauna needs planning permission in England

In England a garden sauna is an outbuilding, and outbuildings at a house can go up without a planning application under permitted development, as long as they stay inside the limits on the Planning Portal's outbuildings page. Break any one limit and you need full planning permission.

The rights cover buildings for a purpose incidental to the enjoyment of the house. The government's permitted development technical guidance gives garden sheds, other storage buildings and garages as examples, and rules out separate living accommodation or an outbuilding used as a bedroom, bathroom or kitchen.

A sauna your household uses is a leisure use of the garden, much like a summerhouse, rather than living space. If you want certainty in writing before you build, the council can issue a Lawful Development Certificate confirming the sauna doesn't need permission.

Height limits for a garden sauna in England

Height is the limit most garden saunas run into, and it changes with the roof shape and how close the cabin sits to the boundary.

The guidance measures height from the ground immediately next to the building, and on a slope from the highest part of that ground. It also says ground level doesn't include anything laid on top, such as decking, so a cabin on a raised timber platform is measured from the soil, not from the platform.

That matters near a fence. A 2.2m cabin on a 300mm timber frame is 2.5m tall for planning purposes, with nothing to spare, so plan the base for a garden sauna and the cabin's height together.

Compare the overall height of any cabin on our best outdoor saunas list with the 2.5m limit, adding the base, before you settle on a spot within 2m of a boundary. Keep every part of the sauna more than 2m from the boundary and the limit rises to 3m or 4m.

Where in the garden a sauna can go

The Planning Portal sets 4 more limits on position and size. A sauna can't go on land forward of the wall forming the principal elevation, which is usually the front of the house. Together with other outbuildings and extensions, it can't cover more than half the land around the original house, meaning the house as first built or as it stood on 1 July 1948.

Verandas, balconies and raised platforms aren't permitted development, and a platform can't be more than 0.3m high. A deck that carries the sauna and a seating area counts, so keep any raised base at or under 0.3m.

On designated land, which covers national parks, the Broads, areas of outstanding natural beauty, conservation areas and World Heritage Sites, outbuildings at the side of the house need planning permission. In national parks, the Broads, AONBs and World Heritage Sites, buildings more than 20m from the house are also capped at 10m² in total.

Listed buildings, flats and other exceptions

Within the curtilage of a listed building, any outbuilding needs planning permission, so a garden sauna at a listed house always needs an application. Permitted development for outbuildings also applies only to houses: flats and maisonettes don't have it, so a sauna in a flat's garden needs permission.

There are 2 exceptions that are easy to miss. The original planning permission for your house may carry a condition removing permitted development rights, and the council may have issued an Article 4 direction removing them across an area, most often a conservation area. Your council's planning department can confirm both.

Garden sauna planning rules in Wales

Wales follows the same pattern with a few differences that catch people out, set out on the Welsh Government's outbuildings page. The biggest: any part of an outbuilding within 2m of the house can't be more than 1.5m tall, so a garden sauna in Wales has to sit at least 2m from the house.

Elsewhere the limits are 2.5m within 2m of a boundary, 4m for a roof with more than one pitch, 3m for a single pitch or other roof form and 2.5m for a flat roof, with eaves no higher than 2.5m. Outbuildings can't cover more than 50% of the curtilage, can't go in front of the principal elevation, and can't extend beyond the side of the house towards a highway.

In a national park, an area of outstanding natural beauty or a conservation area, nothing can go between the side of the house and the side boundary, and buildings more than 20m from the house are capped at 10m² in total. Listed buildings need permission, raised platforms over 300mm aren't permitted, and the allowances apply to houses, not flats or maisonettes.

Garden sauna planning rules in Scotland

Scotland's rules for garden buildings are Class 3A in Planning Circular 1/2024 on householder permitted development rights. A sauna can be up to 4m tall with eaves up to 3m, but any part within 1m of the boundary can't be higher than 2.5m.

It can't go forward of the principal elevation, or of a side elevation that fronts a road, and development can't take up more than half of the front or rear curtilage. In a conservation area the building's footprint is capped at 8m², and within the curtilage of a listed building at 4m², with listed building consent needed if it affects the building's character.

Flats get much less. Class 4B allows a building in a flat's private garden only up to 1.5m tall, 1.2m deep and 2.5m wide, which rules out any sauna cabin without a planning application.

Garden sauna planning rules in Northern Ireland

Northern Ireland's rules are Class D of the Planning (General Permitted Development) Order (Northern Ireland) 2015. A garden building can be up to 4m tall, but within 2m of the boundary the eaves can't be higher than 2.5m, and outbuildings can't cover more than 50% of the curtilage.

It can't sit forward of a wall that faces a road and forms the principal or side elevation, and no part can be within 3.5m of the boundary where a road runs opposite the rear wall. Decks, balconies, verandas and other raised platforms are excluded, and at a listed building you need listed building consent first.

In a World Heritage Site, national park or area of outstanding natural beauty, buildings more than 20m from the house are capped at 10m² in total, and in those areas and conservation areas nothing can go between the principal or side wall and the boundary. The order defines a dwellinghouse as excluding flats, so flats get no permitted development for a sauna.

Building regulations for a garden sauna

Planning and building regulations are separate tests, and a sauna can pass one and still fall under the other. Most garden saunas are small enough to be exempt from building regulations, with conditions.

The England and Wales thresholds are on the Planning Portal's building regulations page for outbuildings and in Schedule 2 of the Building Regulations 2010. Scotland's come from schedule 1 and schedule 3 of the Building (Scotland) Regulations 2004, and Northern Ireland's from schedule 2 of its 2012 regulations.

The exemption doesn't cover the wiring in England. Regulation 9 keeps Part P in force for small detached buildings that take their electricity from the house, so the electrical work for a garden sauna still has to be certified.

Wood-fired garden saunas: extra rules

A wood-burning stove changes the picture in Scotland. Both Scottish exemptions above exclude a building with a fixed combustion appliance, and the small-building one also excludes a flue, so a wood-fired garden sauna there falls outside them and should be treated as needing a building warrant.

Anywhere in the UK, find out if your address is in a smoke control area before you order. The smoke control rules say unauthorised fuels such as wood can only be burned in exempt appliances, and they name a chimney on a garden building such as a summerhouse as covered. In England a chimney that releases smoke can bring a penalty of up to £300.

So a wood-fired sauna in a smoke control area needs a stove on Defra's exempt list, burning only the fuel its maker specifies. Your council's environmental services team can tell you if your address is covered.

What to check before you order a garden sauna

Most of the answers are on your own deeds, a tape measure and the council's website. Work through these in order and you'll know whether you need an application before you pay a deposit.

If every answer is no, a garden sauna for your own use is very likely permitted development. If any answer is unclear, a Lawful Development Certificate costs far less than taking a cabin down.