How sauna fires can lead to multimillion pound losses

  • High temperatures and the presence of timber make saunas a relatively high fire risk
  • Fire can rapidly spread to nearby combustible building construction – posing a risk to people and property
  • A robust risk management process is necessary to keep saunas safe

Saunas are present in an increasing range of occupancies – not only traditional commercial leisure industries such as health clubs, hotels and leisure centres – but also in residential developments and other, similar accommodation.

Saunas pose a relatively high fire risk because of the presence of timber construction, combined with high operating temperatures that are typically achieved by electric heaters.

Heaters are very often positioned close to the combustible walls that form the sauna enclosure. This allows a fire involving the heater to spread rapidly. In full-scale fire tests, the temperature within a sauna enclosure has been shown to rise to 600 degrees centigrade in just a few minutes of fire inception.

Most fires in saunas start in or around the heater, but there can be other causes, such as arson. The risks of fire developing unnoticed are greater where the sauna is not closely supervised.

Risk to life and property

Fires in saunas provide a significant risk to life and can also result in significant property damage, as fire can quickly spread to other elements, such as combustible building construction. Smoke and other dangerous and damaging products of combustion often spread even further.

Sauna fires frequently cause lengthy interruption to business, especially in health clubs, hotels and leisure centres.

Guidance on managing the risks of sauna fires

Fire prevention

  • Saunas should be designed and installed by competent contractors. The design, including fire protection measures, should take account of the intended use. Saunas that are intended to be used unattended, for example those in residential developments where there are no permanently based employees to supervise use, are especially high risk. Speak to Zurich at the early stages of the design process for further guidance.
  • Provide instructions for sauna users and display rules for the safe use of the sauna. This should include prohibiting the use of essential oils, and a ban on newspapers, plastic cups, towels and other loose combustible items being taken into the sauna.
  • Supervision and surveillance – close monitoring of the sauna while in use will help to ensure that it is used in a safe manner, in accordance with the established rules and guidance for users. Saunas should ideally be sited where they can be appropriately overseen, or CCTV cameras should be situated in the area outside the sauna to aid surveillance by site employees, such as those working at a reception desk.
  • Power supplies – the power supply to the sauna heater should be manually switched on at the start of the day, and manually isolated at the end of the day. Automated timers to switch the power on and off should be avoided.
  • Sauna inspections – ensure that saunas are inspected fully before heaters are switched on; at regular intervals – e.g. hourly – throughout the period when the heater is in operation; and at the closedown of the premises.
  • Inspections should focus on: identifying the presence of combustible items on or in close proximity to the heater such as towels, newspapers, moveable timber benches, water ladles and buckets, warning signs etc; identifying damage to the heater or to heater guards that prevent combustible items coming into contact with the heater; and seeking evidence of unsafe use such as tampering with temperature controls. Inspections should be recorded with a checklist to ensure that relevant aspects are covered.
  • Cleaners – a number of fires have been caused by items being placed on or in close proximity to sauna heaters during cleaning activities. Cleaners and other employees working in the sauna should be trained not to place items on or close to heaters.
  • Heater maintenance – fires are frequently the result of poor maintenance of the electrical heaters, which are the primary ignition source. This may result in thermostats not working properly or the failure of over-temperature safety cut-outs. Either may result in overheating and ignition. Sauna heaters need to be maintained regularly in accordance with the manufacturer’s recommendations by a competent contractor, and should be included in planned maintenance schedules.
  • Frequent use of sauna heaters at elevated temperatures – either as a result of poor heater maintenance or inappropriate use – can lead to accelerated degradation of the sauna timber and an increased risk of ignition. Watch out for the timber becoming darkened and almost charcoal-like. Any timber found in this state should be replaced as a matter of priority. The risk can be reduced by installing fire-resisting mineral board to the walls and ceiling immediately adjacent to the heater.

Fire mitigation

  • Fire compartmentation – ideally, saunas should be located in a dedicated area that is separated from the remainder of the building by walls/floors providing at least 60 minutes’ fire resistance, with appropriate matching fire doors installed at entrances. Check that any openings in compartment walls for the running of services and the like are properly fire-stopped with proprietary materials that are also designed to provide 60 minutes’ fire resistance. This particularly applies to those that are out of sight, for example in ceiling voids above the sauna enclosure.
  • Saunas are frequently located on the ‘wet’ side of health clubs and leisure centres, where fire detection is limited or absent. The provision of fire detection in the area adjacent to the sauna and linked to the building’s main fire alarm system will help raise the alarm quickly. The detection will need to be appropriately specified for the environment.

Fire suppression

When automatic sprinklers are not provided to protect the sauna, a water mist system may be used.

Water mist is a suitable form of fire protection for the challenges posed by saunas. It can rapidly absorb heat from the fire – by turning small water droplets to steam – and quench the fire while at the same time rapidly cooling surfaces of the enclosure to prevent re-ignition.

Water mist is referred to as a ‘specific application solution’. For each hazard to be protected, a water mist system must be proven to be effective by acceptable fire test protocols conducted by Zurich-recognised testing laboratories.

The laboratory must issue an independent report documenting the basis of a system’s approval. It must also publish a list identifying the water mist system components – such as nozzles and controls – that form the approved system for the specific application.

Water mist can be accepted as a Zurich-recognised technology for fire protection when the selected water mist system:

  • Is approved, certified or listed by a Zurich-recognised testing laboratory (such as the Danish Fire Laboratories)
  • Passes an independent acceptable test protocol (such as DFL Fire Test Protocol: 131216-105A)
  • Is installed in accordance with a Zurich fire protection standard (such as NFPA 750)
  • Follows manufacturer guidelines