Building and buying

Building a sauna: requirements, construction, types and costs

Torben Schröder

Wellness lovers appreciate the sauna as a place of relaxation for body and soul. If you want to save yourself a trip to the nearest spa, or simply prefer to sweat in a private atmosphere, then why not create your own sauna? Discover which factors you should consider before building a sauna, which construction methods and modes of operation there are, what to take into account for a garden sauna, what’s important for an indoor sauna, and how to build a sauna yourself.

A young man in a bathrobe is sitting in a sauna.
© Getty Images / iStockphoto

In this article

Planning a sauna: factors to consider in advance

A sauna is more than just a few boards that have been put together. When planning your project, you should consider three factors that are relevant for any type of sauna:

  • Size: if several people will be in the sauna at the same time, you must allow approximately one and a half square meters of space per person. For example, if there are four people in your family, the sauna floor area should be six square meters. On the other hand, the sauna should not be any larger because that would increase the heating costs.
  • Seating: regardless of the floor space, each person needs somewhere to sit or lie down, either on one level or on multiple levels. If very tall people will be sitting on a sauna bench, you must take this into account when choosing the type of sauna.
  • Power connection: if you decide to buy a powerful electric heater for your sauna, it may need a high voltage connection.
Close-up of a sauna bench with an infusion bucket on it.

Before building a sauna, consider how many people will be in it at the same time – you should plan the appropriate number of places to sit or lie down.

Different sauna construction methods

There are two ways to build a sauna: the element construction method and the solid wood construction method. These differ mainly in terms of appearance and price. We present both here.

The element construction method

The outside of this type of sauna is not made of solid material, but of several layers that provide insulation for the cabin. It is basically a kit that you can put together yourself with a little bit of skill. Thin wooden panels are alternated with insulation material. A so-called vapor barrier, for example made of aluminum foil, prevents heat and moisture from escaping to the outside.

The main advantage of the element construction method is its flexibility: the sauna can be assembled and disassembled quickly, and additional elements such as windows and benches can be added after the initial construction. Since the parts are industrially manufactured, this construction method is more economical.

The solid wood construction method

In a solid wood sauna, the wood serves both as a building and an insulating material. The thicker the wood, the better the insulation effect. This construction is altogether very stable and inflexible – you must make sure you don’t need to move it in the near future. Boards that are four to five centimeters thick are assembled in a block design: by means of a tongue and groove system, the planks are stacked on top of each other and pressed together with a clamping device. The ceiling is also made of solid wooden boards.

Apart from the durability, the main advantage of a sauna building made of solid wood is the enhanced feeling of well-being. The radiant heat from the solid wood is greater than that produced in an element sauna. It also has a higher-quality appearance.

Various modes of operation

The term “Finnish sauna” is a familiar one. But do you know what it means exactly? It’s actually an operating mode. Saunas can be used in different ways – regardless of the chosen construction method. We present some common alternatives below.

  • A Finnish sauna: typical features are a high air temperature of 80 to 105 degrees Celsius and very low air humidity of 15 percent.
  • A steam bath: the temperature is only 40 to 55 degrees, but the humidity levels are extremely high at 80 to 100 percent.
  • A baby sauna: even in their first year of life, young children are physically ready to spend time in a sauna. Their cardiovascular system is strong enough and their immune system active. However, they should only stay inside for a short time (about three minutes). The maximum temperature is 75 degrees Celsius. You should avoid infusions.
  • A bio-sauna: this gentle operating mode that makes use of essential oils and light therapy is particularly suitable for elderly people and people with high blood pressure. The temperature reaches 50 to 60 degrees Celsius.
  • An infrared sauna: an infrared cabin works quickly. The rays penetrate into the uppermost layers of the skin and heat them up. The sauna only reaches a temperature of about 40 to 45 degrees.
Close-up of a toddler holding an infusion spoon in his hand in a sauna.

Children are allowed to play with an infusion spoon, but not to use it. You must avoid infusions when taking a sauna with babies and toddlers.

The choice of location: a garden sauna

When choosing the location, you basically have two options: inside or outside the house. A garden sauna is very practical as you tend to have more space outdoors than indoors. In addition, the natural proximity to nature makes it easy to cool down: just step out of the sauna door into the open air.

If you opt for a sauna in the garden, you still have to decide on the size you want. There are also a few building regulations to be followed.

Observe the regulations for a garden sauna

Before installing a garden sauna, you should check whether you need to obtain permission – just like for a shed or summer house. The regulations for structural changes in and around the house vary greatly in different cantons. You will find the regulations in the relevant cantonal legislation. Alternatively, you can also obtain information from the local building authority.

Determine the size of the garden sauna

The more space you have in your garden, the larger your sauna can be, for example in the form of a sauna house. But make sure that there is still enough room for other purposes, such as gardening and games for the children. We present three types of sauna, from smallest to largest:

  • For small gardens, a standing sauna barrel is a good idea, for instance. With a diameter of only 2.44 meters, the version from Chalet und Blockhaus-Center Dannler is very compact. This sauna made of Siberian spruce is delivered as a kit with benches, door, windows and a sauna stove. The price for the basic version is 4,499 francs (price on 16 October 2020).
  • There is room for horizontal sauna barrels in medium-sized gardens. The basic price of the three-meter-long Tünni sauna barrel is 4,980 francs (price on 16 October 2020). It costs more depending on the configuration. For example, you can choose the type of wood and various types of windows and stoves.
  • With a length of 4.26 meters and a width of 2.76 meters, the “Woodfeeling” sauna house, available at my-wood-shop, has the dimensions of a small patio. It consists of 38-millimeter-thick wall boards made of Nordic spruce and is mounted using the plug/screw system. It costs 4,215 francs (price on 16 October 2020).
A horizontal sauna barrel stands at the end of a garden just in front of a lake. There is a woman wrapped in a towel inside.

The horizontal barrel is a common sauna shape, which is suitable for most gardens

The choice of location: an indoor sauna

If you have unused space inside your house, the construction of an indoor sauna is a good idea. The choice of location plays a particularly important role.

Determine the location of your indoor sauna

In the basement, in a large bathroom, in the attic – there are several places where it is possible to build a sauna. Below we give you some tips on what you should pay attention to:

  • Allow enough space: on the one hand, the sauna cabin itself requires sufficient open space. The “Bergen 1 Classic” solid wood sauna, for example, has a floor area of 198 x 148 centimeters. At 203 centimeters, its height is not to be sneezed at. Finally, the sauna should be placed ten centimeters from each wall and ten centimeters from the ceiling. You should also plan space for the cabin structure. In the rarest cases, a sauna can be set up outdoors and then transported into the house in one piece.
  • Check the ventilation: this is a very important factor, especially for indoor saunas, as they are usually located in closed rooms. A sauna produces a lot of moisture, which should not be allowed to settle permanently in the room. You must therefore make sure that the location is as dry as possible, as well as being sufficiently heated and well ventilated. This will not necessarily be the case, especially with an older, poorly insulated basement. This can be remedied with new basement ceiling insulation.
View into a sauna. An infusion bucket and towel are draped on a bench. Daylight is shining in.

The basement is a suitable location for an indoor sauna. However, you should make sure that moisture can escape easily.

Observe the regulations for an indoor sauna

There is no need for a building permit when installing an indoor sauna as long as the house or apartment belongs to you. When it comes to the sauna stove, please note that coal-fired units must be inspected by a chimney sweep. An electrically operated stove should be installed by a specialist, as it requires a high voltage connection.

Building a sauna yourself

With a bit of manual skill, you can build your own sauna from A to Z. Below we explain how to make a sauna house with a flat roof in the garden according to the block construction method.

Draw a floor plan

Draw your dream sauna on graph paper. The most important elements are the external dimensions, i.e. total length times width, the dimensions of the inner benches, and the positioning of the stove, door and windows.

Lay the foundation

To make sure the garden sauna will stand firmly on the ground, you need a stable base in the form of a foundation plate. To make this, mark out the designated area in the garden with cords and pegs – the dimensions should be about ten centimeters larger than the outside dimensions of the sauna. Then dig out the surface to a depth of 30 centimeters. This pit should first be shuttered with robust boards and then filled with a layer of gravel about 15 centimeters deep. The gravel must be compacted and covered with a polyethylene film. This protects the concrete, which is poured in next, from ground frost.

Purchase the necessary material

You can get the wood from a specialist trade store. On the one hand, you should make sure you choose high-quality material so that you can enjoy your sauna for many years to come, and on the other, you should opt for an existing profile, i.e. a tongue and groove connection, for easy assembly. Sauna wood is more expensive than commercial wood. Spruce, cedar and aspen are good choices, for instance. These types of wood have a low thermal conductivity, do not resinate and do not splinter. Solid block planks are suitable for the outer shell, and slightly thinner planks should be chosen for the roof and floor. Sauna wood is always used untreated. Sauna doors and sauna benches are available as prefabricated parts.

Build the substructure

Now the actual construction work begins. Make sure that you are careful when cutting all the wooden parts. No air should be allowed to enter the sauna cabin from outside. First of all, mount the base frame of the sauna on the ground: the foundation timbers need to be bolted together. Slide the moisture barriers made of rubber granules between the concrete foundation and the wooden construction to protect the sauna house from moisture. To ensure maximum stabilization, you can screw the base frame to the concrete foundation.

Put up the walls

Screw the first block planks to the substructure. The walls should then be quite quick to put up thanks to the tongue and groove system. If the planks do not interlock, a rubber mallet will help. Leave the necessary space free for windows and doors. The windows should be installed as soon as the walls are at least half the height of the window.

Put the roof on

The roof of a sauna house is also made of tongue and groove boards, but they are usually slightly thinner. Place these boards at a 90-degree angle to the erected walls, i.e. crosswise. Roof insulation is recommended – it’s best to use the principle of on-roof insulation: attach roof battens on the roof boards, leaving a large distance between them. Fill the resulting gaps with insulating material. Here too, the joints are ensured by tongue and groove boards. Last but not least, stick EPDM foil onto the finished flat roof to seal and protect it against weathering.

Interior fittings

First cut insulation boards to size and place them in the gaps in the floor substructure. The floor timbers should now be inserted into one another and screwed together tightly. Cut baseboards to size and place them in a single layer around the sauna cabin. For the walls, wall battens are sawed and attached according to a similar principle. The last step is to install the sauna benches, which are supplied ready for assembly, and to insert the door into the recess.

Conclusion: building a sauna – it’s easier than you think

Whether you have your sauna delivered as a finished product or put it together yourself – building your own sauna will create a spa in your own home. In principle you only need sufficient space, for example in the garden or in the basement. The costs of the sauna house etc. are kept within limits and the regulations are usually easy to comply with.

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