Garden saunas: planning, power and where to put one

Planning permission

• It counts towards 30 m². A sauna, shed and garden room together must stay within 30 m².
• 25 m² of garden must remain after it goes in.
• Behind the front of the house, and within the height limits: 4 m with a tiled or slated pitched roof, 3 m otherwise.
• Home use only. A sauna you rent by the hour or open to the public is a commercial use that needs permission.

Power and heaters

Compact electric saunas are commonly sold with heaters of around 6 kW, and larger ones more. That's several times the load of a garden office.

• Tell the electrician the heater's rating before the cable is laid, so it's sized correctly.
• Your fuse board may need space or capacity for a new circuit.
• Wood-fired heaters avoid the electrical load but need a proper flue and safe clearances.

Where to put it

• On a solid, level base that drains well. See foundations.
• Close enough to the house to keep the cable run short.
• Somewhere private, with a short path to a shower or cold plunge if you want one.
• For wood-fired saunas, away from overhanging trees and with smoke drifting away from neighbours.

Sauna plus garden room

Some suppliers sell garden rooms with a sauna built into one end. It saves space and a second base, but plan the ventilation carefully so heat and moisture don't reach the rest of the room, and remember the whole building counts towards the 30 m².