Create an Outdoor Sauna Room

The Finnish people definitely got it right when they invented outdoor sauna rooms! A sauna is perfect for cleansing, relaxing and calming both body and mind. And what better retreat from the average fast-paced, stressful and hectic modern lifestyle, than a home sauna in your garden?

How Does An Outdoor Sauna Room Work?

Understanding how saunas function is important if you’re considering erecting your own special sauna room. A Finnish sauna in its most basic and traditional form works as a room, where humidity and temperature is controlled through the production of steam. The most common way of creating steam in an outdoor sauna room is by sprinkling water on volcanic peridotite rocks that have been heated on a special stove. Outdoor saunas tend to be more desirable than house saunas, as it is easier to ventilate a sauna outside than indoors.

The increase in temperature and humidity then promotes the cleansing, relaxing and rejuvenating process of sweating. It is for this reason that a sauna should ideally be located outside or close to a shower room, where the body can be periodically cooled and washed with cold water. The colder the contrasting temperature, the better! This is partly why sauna rooms are popular as outdoor garden buildings, particularly in colder climates.

The more modern equivalent is also known as a far infrared sauna, or just infrared sauna for short. It basically works on the same premise of heating the air to raise the body temperature, but uses infrared light instead of steam to do so. This means that the air is not as heavy and difficult to breathe, and the infrared light is safe for skin.

However, when choosing a site for your sauna, with both traditional and modern saunas, you should note that to make the best of the relaxing and cleansing treatment, you’d need to strip off completely. So perhaps choosing a location where the neighbours won’t catch a glimpse of you in all your glory is your best bet!

Will I Need Permission to Build My Outdoor Sauna?

Generally, a sauna building can be constructed in your back garden without buildings regulation approval, as they rarely exceed more than 15 square metres in floor area.

However, in the event that you choose to install or build a sauna with a floor area of between 15 and 30 square metres, building regulations approval won’t have to be sought, providing that the “building is either at least one metre from any boundary or it is constructed of substantially non-combustible materials”.

With regards to planning permission, a sauna is generally considered as an ancillary garden building, and as such is classified as an outbuilding. Planning permission regulations can depend according to your local planning authority and it’s by laws. However as a guideline, you will most likely only require planning permission in the following scenarios:

  • You want to put up a building or structure which would be nearer to any highway than the nearest part of the “original house”, unless there would be at least 20 metres between the new building and any highway. The term “highway” includes public roads, footpaths, bridleways and byways.
  • More than half the area of land around the “original house” would be covered by additions or other buildings.
  • The building or structure is not to be used for domestic purposes and is to be used instead, for example, for parking a commercial vehicle, running a business or for storing goods in connection with a business.
  • You want to put up a building or structure which is more than 3 metres high, or more than 4 metres high if it has a ridged roof. (Measure from the highest ground next to it.)
  • If your house is a listed building.
  • If you live in a Conservation Area, a National Park, an Area of Outstanding Natural Beauty, or the Broads, and you want to put up a building or structure with a volume of more than 10 cubic metres (though it might be allowable as an extension)

Outdoor Sauna Room Building Material

If you’re thinking about creating an outdoor sauna room, your best bet is to opt for a timber structure. Timber is the best material for sauna rooms, as it can contract and expand with the heat fluctuations, and does not promote the growth of moisture loving moulds. Sauna rooms tend to be build from untreated cedar, pine or knot-free hemlock. Cedar in particular retains properties that help keep sauna rooms clean and mould-free.

If you have an ideal location, you’ll first need to make sure that the ground is suitably level. A basic traditional sauna can be modelled on your average shed design – 4 walls, a door and a window if desired. However, a sauna will need at least three ventilation points. You’ll need a vent above the heater, one near the top of the sauna, and one at the base (leaving a good two or three inch gap under the door may suffice).

The sauna room can be insulated with 3” fibreglass, and then clad in untreated cedar wood or spruce. The floor may need a small drainage exit so that any moisture on the floor doesn’t accumulate and cause problems. You should also make sure that any rough edges are smoothed, and nail heads should be covered, as they will conduct heat. Any electrics or lighting will need to be installed by a professional electrician.

Your sauna will only require a few sparse accessories – perhaps a hook for hanging your clothes or dressing robe outside, and an untreated wooden bench to sit on. The sauna stove heater size will depend on the size of your sauna, but the guideline is that you need one kilowatt per 45 cubic feet.

Sauna Kits

There are a plethora of sauna plans and self-assembly pre-fabricated sauna kits available on the market. These are made to specification or available in set dimensions in the factory, and are shipped out to the buyer. Most look fairly simple in style, resembling log cabins that won’t look out of place surrounded by a few choice garden plants. The average sauna kit will most likely cost you around £3,000 – £5,000. An outdoor sauna room can range in size from 4’ x 4’ for one person, to 12’ x 8’ to accommodate many people. It’s not uncommon to be able to modify the basic sauna kit design at a cost – for instance, changing the specified roof tiles, the thickness of the logs or adding decorative features.

Sauna Tips

To make the most of your sauna, try using it without any clothes on! This allows your whole body to sweat and release toxins through the skin. Wearing an old swimming costume is not advised, as they may still contain chemicals from swimming pools, which can then be released into the air under the hot, humid conditions.

Saunas should be relatively easy and trouble free to use and maintain. However, another useful tip is to undertake regular cleaning of your sauna. Although it should stay relatively clean on it’s own, a cursory but regular once-over will eradicate breeding conditions for bacteria and fungal spores. Try to use non-toxic natural products that will not penetrate or damage the wood.