Garden sauna planning permission in the UK.

This is general guidance to help you ask the right questions, not a substitute for checking with your local planning authority. Rules differ across England, Scotland, and Wales, and even within England they vary by council.

Permitted development, in outline

In England, many garden outbuildings, including saunas, fall under "permitted development", meaning they don't need a separate planning application. Generally this depends on the outbuilding being single-storey, sitting behind the principal elevation of the house, not exceeding certain height limits (typically around 2.5–4m depending on proximity to a boundary), and not covering more than 50% of the garden alongside other outbuildings.

A Kemi or Koli, at roughly 2.4m overall height, comfortably sits under the usual height thresholds for most standard placements, but "usual" is doing a lot of work in that sentence, which is exactly why this needs checking against your actual property.

Where permitted development doesn't apply

A few common situations remove or restrict permitted development rights:

• Listed buildings: any outbuilding in the curtilage of a listed building typically needs consent.
• Conservation areas: outbuildings behind the house are more restricted, and some councils apply tighter rules generally.
• National Parks and Areas of Outstanding Natural Beauty: size limits are often reduced.
• Flats and maisonettes: permitted development for outbuildings generally applies to houses, not flats.
• Article 4 directions: some local authorities remove specific permitted development rights in defined areas; these aren't always obvious from looking at a property.

How to check your own property

The reliable way to find out is to contact your local planning authority directly, or apply for a LAPDC (Lawful Development Certificate) if you want written confirmation before committing to a build. Our own site appraisal reviews your specific property as part of the wider survey (access, ground conditions, electrical capacity), but it's not a substitute for your council's own determination if there's any doubt.