Mobile Sauna Towing & Licensing: UK Law Explained
Since December 2021, anyone with a full Category B (car) driving licence in the UK can tow a trailer up to 3,500kg. A mobile sauna on a braked trailer is legal to tow on a standard car licence, provided your vehicle’s towing capacity isn’t exceeded and the trailer meets road-legal requirements (lights, plate, brakes if over 750kg).
Licence categories explained
The key change came in December 2021, when the rules for car drivers were simplified. Drivers who passed their car test from 1 January 1997 onwards can now tow trailers up to a combined 3,500kg on a standard Category B licence — the previous requirement to pass a separate B+E test was dropped. Drivers who passed before 1997 generally have wider entitlements already.
In practice this means the vast majority of people can tow a mobile sauna without any extra test. If you plan to tow something much heavier, or to drive larger vehicles, check whether you need category C1 or B+E — but a standard mobile sauna setup is normally covered by an ordinary car licence.
Weights — what a mobile sauna weighs & what you can tow
Two numbers matter. The first is the trailer’s maximum authorised mass (MAM), sometimes called gross weight — the most it can legally weigh fully loaded. The second is your vehicle’s towing capacity (its maximum towing mass). The loaded sauna must stay below both, with sensible margin.
A mobile sauna’s weight depends on its size, the timber used, the heater and the trailer itself. Many builds sit comfortably within a 3,500kg braked-trailer limit, but you should always work from the actual figures for your build and tow vehicle rather than a rule of thumb. We’ll confirm the weight of your sauna as part of the build so you can match it to the right vehicle.
Braked vs unbraked trailers
UK law requires any trailer with a maximum weight over 750kg to have a functioning braking system. A mobile sauna is comfortably over this threshold, so it will always be a braked trailer. Braked trailers also need a breakaway cable (or secondary coupling) that applies the brakes if the trailer becomes detached.
Tow vehicle requirements
- A towbar and electrics rated for the trailer’s weight
- A towing capacity (in the handbook/VIN plate) above the loaded sauna weight
- Correctly rated towing mirrors if the trailer is wider than the vehicle
- Awareness of your gross train weight — vehicle plus loaded trailer combined
Road-legal must-haves
To be legal on the road, a mobile sauna trailer needs working road lighting (rear, brake, indicator and number-plate lights), a number plate matching the towing vehicle, a secure coupling and breakaway cable, and properly rated tyres. Loads and the structure must be secure for transport. Our trailers are built to these requirements as standard. See what’s included in every build.
Driving & towing safely
Towing changes how a vehicle behaves: longer stopping distances, wider turns and reduced speed limits on some roads apply when towing. Distribute weight so the trailer is nose-heavy within its limits, check your coupling and lights before every journey, and build in extra time. If you’re new to towing, a short towing-awareness course is a worthwhile investment before your first event.