Sweat it like Beckham:
How to create your own sauna in the UK
Whether you are upgrading a luxury spa or embarking on a modest DIY project at home, the key principles of sauna construction are the same for everyone.
by Adam Rang & Anni Oviir.
Article last updated: November 2019.
Saunas have been enjoyed across Britain and Ireland for thousands of years. Seriously.
The oldest sweat lodge ever discovered was from 3,500 BC at Marden Henge, close to Stonehenge, while evidence of ancient saunas have been found elsewhere on these isles, such as Little Cattwick in Yorkshire. Gaelic saunas, known as teach allais, were used in parts of Scotland and Ireland until the 18th century.
More recently, Brits have been rediscovering their sauna heritage with a little help from their friends around the world. Different styles of sweat bathing have been brought to the UK by the Romans, the Victorians, and eventually the Finns - which is why we now use the Finnish word 'sauna' in English too.
This Nordic sauna tradition, which spread to the UK in the 20th century, is rooted in the culture of Finno-Ugric peoples living around the Baltic Sea, which also includes the Estonians. There is now a renewed interest in saunas across the UK - and the Estonians are now at the forefront helping more Brits build saunas with their expertise, world leading technology and creative Nordic design. This has been helped by a few celebrity fans of Estonian saunas, such as David Beckham and Guy Ritchie.
Key principles of sauna construction
The sauna is an ancient innovation that can be broken down into three discoveries by early humans in the stone age:
Fire can be controlled.
Stones can absorb the power of fire and gently release it over time.
Pouring water on those stones can enable us to bathe in the power of fire.
Saunas have evolved a lot through the ages since then, but the basic principles remain the same. The key feature is the stones, which radiate the warmth and periodically convert splashed water into steam for bathing. This sauna steam is known as leil in Estonian or löyly in Finnish, which also translates as the 'soul' of the sauna.
A sauna can be built inside a building, usually as part of the bathroom in a residential property, or as a separate building.
An outdoor sauna is usually classified as an ancillary building and must be built in line with local planning regulations, which can vary across the UK. Generally, however, most saunas built at home in the UK do not exceed 15 square metres are so are no more complicated than a shed. A building between 15 and 30 square metres will need to be at least one metre from a boundary and constructed of substantially non-combustible materials. Other factors likely to complicate the construction of a sauna, includes building it closer to public roads than the main house unless there is at least 20 metres in between, covering more than half the land around the house, using it for commercial reasons, building it more than three metres in height (or 4 metres with a ridged roof), building it next to a listed building or within a specially protected area. The good news is that these do not apply to most saunas that people want to build, but always check local rules thoroughly.
Regulations aside, you probably have other considerations weighing more on your mind for an outdoor sauna, such as space, aesthetics, electrification and privacy. It's a great idea to have a bench and some kind of cold water to immerse yourself in outside, such as a tub, but you probably don't want your neighbours seeing you while you do that!
An outdoor sauna may have more rustic charm, but an indoor sauna can be more luxurious and comfortable - and just as authentic. You also have the advantage of easily using your existing bathroom for cold showers during saunas sessions, as well as changing and washing.
For Estonians, the sauna was the only room for bathing and would be built either inside the home (attached to the kitchen) or in a separate building. In fact, many Estonians would traditionally build their sauna building before their main home and then live in it when needed too. This could just be the hot room, known as the leilruum in Estonian, although it may include additional facilities such as washroom, changing and relaxation room. For the simplest of saunas, only a hot room is required and washing can take place in there afterwards or in your regular bathroom.
A shed provides a good basis for this type of construction project, although there are additional considerations that are unique to a sauna, such as materials, ventilation, drainage, and door safety.
Wood isn't just chosen for sauna construction just because it looks nice. The wooden walls must be able to expand and contract with the extreme heat fluctuations and also withstand considerable moisture without accumulating mould. Knots within the wood must also be avoided as these can melt. Untreated cedar, spruce, pine and hemlock (without knots) are all good options. The flooring of an outdoor sauna is often wooden, although a typical bathroom floor is already suitable for an indoor sauna. Just remember that you will need to clean and often drain water away from the floor of a sauna.
The importance of ventilation in a sauna must not be overlooked. This keeps the air fresh, circulates heat and is vital to a refreshing sauna experience. Too much ventilation can remove the heat, but too little can make you feel drowsy and unwell so careful planning is needed for both incoming and outgoing channels. You should consider at least three points of ventilation - one near the floor, one above the heater, and one near the top of the sauna.
The sauna door should open outwards and not use any kind of mechanism, such as a handle or lock. Unless your hot room opens directly outside, the door can be made out of glass and a gap beneath it can provide one of the points of ventilation. The HUUM stoves that we deliver also include a small safety device for detecting when the door is open, which automatically shuts off the heater.
Finally, pay special attention to the risk of people burning themselves such as by touching metal surfaces or having to sit and move around too close to the stove.
Choosing your sauna stove
There are three main considerations here: heating source, style, and size.
We deliver HUUM stoves in both electric and wood-burning versions. Wood-burning can be an appealing option, although you will need to consider local regulations and also the practicality of buying and storing wood. The electric stoves from HUUM however have been designed to replicate the feeling of a wood-burning stove, but combined with advanced new technology for both convenience and safety. You can use either an UKU controller on the wall or a mobile app anywhere to see the current temperature of the sauna and set your target temperature, as well as set a timer. This will enable you to ensure your sauna is the perfect temperature when you need it, such as when you arrive home after a long commute or exercise.
There are two many styles made by HUUM, both of which are designed to keep all the focus on the stones as the key feature. The first is the DROP, which is inspired by the shape of a drop of water, and is attached to a wall. A full overview of specifications for the DROP is available here, while the manual can be downloaded here.
The second if the HIVE, which is free standing and suitable for slightly larger saunas. A full overview of specifications for the various different types of HIVE stoves are available here, while the manuals can be downloaded here.
The DROP is only available as an electric stove, while the HIVE is available as both an electric and wood-burning stove, including one version that is heated from the opposite side of the wall.
HUUM stoves are suitable for sauna hot rooms ranging from 3 to 35 cubic metres. We use kW to measure the output energy of sauna stoves, whether electric or wood-burning. As a general rule, you will need about 1 kW of power for every 1 cubic metre of room that you are heating, although slightly more if there are windows, a glass door, or heat-storing surfaces such as brick, concrete or large logs.
Here's a guide to suitable stove sizes that we deliver:
There are three ways to connect an electric stove to the controller on the wall where you can choose your temperature and even set a timer so it is ready exactly when you want it.
The first is a local connection that provides a direct link by wire between them, but there are also two options that are wireless and also enable you to use a mobile app to control the sauna. There is a GSM version, which uses an internal SIM card to connect the stove and controller by mobile. This comes with a modest annual fee after the first year. Finally, the newest and most sought-after option is a WiFi connection, which has no annual fees.
Wiring for electric stoves
An electric sauna stove must always be installed by a certified electrician. If your electrician is unfamiliar with the installation of an electric sauna stove purchased from us then we are happy to provide them with further guidance, including by speaking to them directly on your behalf. We are also currently developing partnerships with certified electricians across the UK to make this process even smoother for our customers.
There are two options for wiring an electric stove: 1-phase and 3-phase wiring. 1-phase is most common in UK homes and small businesses (unlike elsewhere in the world), while 3-phase wiring is most common for commercial properties in the UK. If you have any doubt at all about the correct wiring for your property, check your electricity bill or box - or speak directly to your electricity provider. Always use a certified electrician for installation.
All HUUM stoves are compatible with 1-phase wiring up to 9 kW (and are delivered with extra instructions for this), while all HUUM stoves of all sizes are compatible with 3-phase wiring. Here's an overview:
The stones are the most important feature in any sauna. In recent times, sauna stoves have become a bit clunky with lots of metal overshadowing a smaller number of stoves. That's why HUUM started with the principle that the stones are the key feature. A large number of exposed stones delivers a superior steam.
A good sauna stone has to accumulate heat, release it slowly and be heat resistant. For this purpose, dense and heavy stones are a good option. The grey rounded volcanic stones that we deliver are known as olivine diabase and were collected in Finland. Olivine diabase is a very heavy stone with a density of approximately 3.5 kg/dm3. It is highly valued as a sauna stone for its durability and high heat capacity.
We have two different size ranges: 5-10 cm (which comes in 15kg boxes) and 10-15 cm (which comes in 20kg boxes). These are highly recommended for HUUM stoves to support both the visual design as well as the optimal sauna experience, but you are welcome to use your own stones that you collect or purchase from elsewhere.
Please note that some types of stones are less effective in saunas, while some can even break and be dangerous. If you are unfamiliar with the right types of stones to be used in saunas then always use a reputable supplier.
Here's an overview of how many you need to order to fill each of the stoves available in our online shop:
Whether you build a sauna with our help or not, the most important thing is that you build it and keep this heritage and joy alive.