Planning a garden sauna

• Single storey only
• No more than 2.5 metres tall within 2 metres of a boundary
• Elsewhere, up to 4 metres with a dual-pitched roof or 3 metres with any other roof, and eaves no higher than 2.5 metres
• Not in front of the house
• Together with extensions and other outbuildings, it covers no more than half the land around the original house

In a conservation area, National Park, National Landscape, the Broads or a World Heritage Site, nothing can go at the side of the house. Outside conservation areas, those places also limit buildings more than 20 metres from the house to 10 square metres in total.

Source: Planning Portal, outbuildings

• No more than 2.5 metres tall within 2 metres of a boundary
• No more than 1.5 metres tall within 2 metres of the house
• Elsewhere, up to 4 metres with a dual or hipped roof, 3 metres with a single pitch or 2.5 metres with a flat roof, and eaves no higher than 2.5 metres
• Not in front of the house. Beside the house, it can be no nearer a road than the side wall of the house, which mainly matters on corner plots
• All outbuildings together cover no more than half the garden

Source: Welsh Government, outbuildings

• No more than 2.5 metres tall within 1 metre of a boundary
• Elsewhere, up to 4 metres overall with eaves no higher than 3 metres
• Not in front of the house, or beside it where that side faces a road
• No more than half of the front or rear garden, whichever it sits in, can be built on

In a conservation area the footprint is limited to 8 square metres, and in the garden of a listed building to 4 square metres.

Source: Scottish Government, householder permitted development

• Eaves no higher than 2.5 metres within 2 metres of a boundary
• Up to 4 metres overall
• Not in front of or beside the house where that wall faces a road
• At least 3.5 metres from a rear boundary that faces a road
• All outbuildings together cover no more than half the garden

In a conservation area, World Heritage Site, National Park or Area of Outstanding Natural Beauty the limits are tighter, so check with your council.

Source: Planning (General Permitted Development) Order (Northern Ireland) 2015, Class D

These rarely apply to the building itself. In England, Wales and Northern Ireland a detached garden building of up to 15 square metres with no sleeping accommodation is normally exempt, and the largest Hekla garden sauna covers under 6 square metres. The electrical work is still covered, as step five explains. If you choose a wood-burning stove, confirm with your building control team or a HETAS registered installer.

In Scotland a small garden building is exempt from a building warrant if it has an electric heater, as long as it is either more than 1 metre from the house or at least 1 metre from every boundary. A building with a stove and flue is not exempt, so a wood-fired sauna needs a building warrant.

Source: Planning Portal, building regulations for outbuildings

A 6 to 9 kW heater needs a dedicated circuit. In England and Wales a new circuit to a garden building is notifiable work under Part P of the building regulations, and a sauna counts as a special location for electrical safety. Use an electrician registered with a scheme such as NICEIC or NAPIT, who can certify the work themselves. In Scotland and Northern Ireland the work must also meet the wiring regulations.

Your electrician will usually visit twice. The first visit is before the base goes down, to plan the cable run. The second is after the build, to drill the cable entry, connect the heater, lights and controls, then test and certify everything. The sauna should not be used until that is done.

Many towns and cities are smoke control areas. In England the rules apply to chimneys on any building, and government guidance names summerhouses. Inside a smoke control area you can only burn wood in a Defra-exempt appliance, using a fuel its manufacturer approves, and councils can issue a penalty of £175 to £300 for chimney smoke. Wales has followed the same system since July 2025.

Source: GOV.UK, smoke control area rules

Your council’s website will tell you whether your address is in one. If it is, ask your stockist whether the stove you want is exempt before you order.

Keep the flue well clear of fences, trees and neighbours’ windows. Burn only dry, seasoned wood. In England, logs sold in small quantities carry a Ready to Burn mark, which means a moisture content of 20 percent or less. Dry wood burns hotter and makes far less smoke.

Expect a slower warm-up and a fire to tend. For many people that is half the appeal.

Usually not. A garden sauna normally counts as an outbuilding under permitted development, as long as it is behind the front of the house, within the height limits, and together with extensions and other buildings takes up less than half the garden. Check with your council if you live in a flat, a listed building or a protected area such as a conservation area or National Park.

A flat, level, solid and permanent base, finished before the sauna arrives. A concrete slab is ideal, and reinforced paving on a solid sub-base also works. Grass, gravel and soft ground are not suitable.

At least a metre on every side, for the build and for maintenance later. The access route from the road needs to be at least a metre wide.

Yes. A 6 to 9 kW sauna heater needs its own circuit, fitted by a qualified electrician. In England and Wales this is notifiable work, so use an electrician registered with a scheme such as NICEIC or NAPIT.

Only if the stove is a Defra-exempt appliance, burning a fuel its manufacturer approves. The rules cover chimneys on garden buildings as well as houses. Check your council’s website to see if you are in a smoke control area, and ask your stockist whether the stove is exempt.

Yes. Hekla saunas come as a kit of pre-made panels, and two people can assemble one. If you would rather not, your Hekla stockist can build it for you. The electrical connection must always be done by a qualified electrician.