5 common mistakes to avoid when buying a sauna

A well-planned sauna purchase can turn your home into a personal spa. Buying a sauna is exciting, but it's also easy to overlook crucial details along the way. First-time buyers, especially those looking at outdoor saunas, often make similar mistakes that can turn a dream investment into a frustrating experience. In this guide, we cover five common sauna-buying mistakes (from sizing and ventilation to quality and installation) and explain how to avoid them. With these sauna-buying tips, you'll be able to make an informed purchase that will deliver years of relaxation and wellbeing.

1. Choosing the wrong size

One of the most common mistakes is buying a sauna that isn't the right size for your needs. Too large, and you waste space (and energy) heating a volume you don't use; too small, and you'll feel cramped every time you try to relax. Think about who will use the sauna regularly — just you, or do you expect family and friends to enjoy it too? Consider the location as well: an indoor sauna needs to fit the room (with enough space for ventilation and safety), and an outdoor sauna needs to fit your garden or patio. Always measure the available area carefully, allowing for both the external dimensions and the internal bench space for comfortable seating. By matching sauna capacity to the number of users and the space you have, you'll avoid the disappointment of a cramped sauna or the wasted resources of one larger than you need.

Saunamo Cubus 8-person sauna installed for a customer

Tip: when in doubt, go slightly larger if you regularly host guests — you can always enjoy the extra room, but you can't stretch a small sauna to fit more people.

2. Ignoring ventilation needs

Forgetting ventilation is a serious mistake that affects both your comfort and the longevity of your sauna. Proper airflow makes a huge difference to how comfortable and safe your sauna feels. Without good ventilation, the heat can become stifling, oxygen levels can drop and humidity can linger, leading to mould or wood damage over time. Every sauna — even a small outdoor barrel — should have ventilation openings or a clear plan for airflow. Typically, a sauna design includes a lower intake vent (usually near the heater) and an upper exhaust vent on the opposite wall or ceiling, allowing fresh air to circulate and 'used' air to escape. Good ventilation not only keeps CO₂ levels safe and prevents stuffiness, it also helps the sauna dry between uses, reducing the chance of mould and odours.

How to avoid this mistake: choose a sauna model with built-in vents or be ready to add ventilation during installation. For indoor saunas, make sure you vent humid air outside (or to a suitable adjacent space) to protect your home. For outdoor saunas, you can vent to the outside air or simply ensure the structure has the recommended airflow openings. Don't seal your sauna so tightly that no fresh air enters — in fact, a well-ventilated sauna feels warmer and more pleasant because the air circulates properly over your skin. In short: plan ventilation from the start and you'll extend the life of your sauna and make every session far more comfortable.

3. Cutting corners on quality materials

Cutting corners on quality is a fast track to regret when buying a sauna. It can be tempting to choose a cheap kit or lower-grade materials to save money up front, but remember: a sauna is an investment built to last for years. Not all sauna materials are created equal — especially the wood. Low-quality or unsuitable wood can warp, crack or even encourage mould in the heat and humidity of a sauna. For example, softwoods like aspen, alder and cedar are popular for their ability to handle heat and moisture; they're naturally rot-resistant and stable, making them ideal for outdoor sauna cabins. By contrast, cheap untreated wood or plywood can crack or release resinous or even toxic odours when heated. Build quality matters too — thin walls with poor insulation will lose heat, and flimsy hardware or benches can fail quickly.

Saunamo installation for a customer in the Azores, where weather can be unpredictable

To avoid this mistake, don't compromise on quality: invest in a well-reviewed brand or manufacturer known for durable construction. Look for saunas built with high-quality materials (for example, aspen, alder, cedar) and quality heaters from trusted brands. It's also worth checking the warranty and support — a reliable sauna supplier will stand behind their product.

At Saunamo, we use only the highest-quality materials in our saunas, so customers can feel confident they're investing in a sauna built to the highest standards. A very low price might save you a few euros now, but if the unit deteriorates or needs constant repairs, you'll end up paying more in the long run. By choosing a sauna built with quality in mind, you'll enjoy better performance, longer life and real peace of mind.

4. Choosing the wrong type of heater

There are several types of saunas and heating technologies, and buying the wrong type for your goals is a common mistake. The two main categories are traditional saunas (heated to high temperatures with a heater and stones, where you can pour water for steam) and infrared saunas (lower temperatures, using infrared panels to warm the body directly). Each offers a different experience: if you want intense heat and steam (the classic burst of löyly), choose a traditional sauna; if you prefer a gentler heat for longer sessions, an infrared sauna may be the better choice. There are even hybrid models that combine both, but make sure you understand the trade-offs before choosing.

Choosing the wrong type can leave you disappointed — for example, someone who loves the classic Finnish sauna ritual (with bursts of steam) won't be satisfied with an infrared sauna, and vice versa.

Another aspect is choosing the right size of heater. The heater is the heart of your sauna, and its importance can't be overstated. A small or cheap heater will struggle to reach the right temperature and can wear out faster from running too hard. Always match heater capacity to the size of your sauna (manufacturers usually specify how many cubic metres a heater can handle). For traditional electric heaters, this often means installing a dedicated 220–240 V circuit — many larger units aren't simply plug-and-play on a standard socket. Failing to allow for this electrical requirement is a major mistake (one that may need an electrician to put right later).

If you're considering a wood-burning outdoor sauna, make sure you're prepared for what that involves: you'll need a chimney or flue for proper ventilation, a wood supply, and possibly local permits if wood smoke is regulated in your area. Wood-burning heaters offer authentic, off-grid charm, but they take more planning and effort (tending the fire and clearing ashes) than electric heaters. In short, choose the type of sauna and heater that suits your lifestyle. Do you want the convenience of pressing a button to heat up (traditional electric or infrared) or romance a crackling fire in a cabin? Do you need the intense 80–90 °C sweat with steam, or are you happy with a 50–60 °C dry heat? Think these questions through carefully. To avoid this mistake, research the pros and cons of each sauna type and consult experts where helpful. At Saunamo, we can explain the differences and help you choose a sauna that meets your expectations, with no unwelcome surprises.

5. Overlooking installation and site planning

Buying a sauna without planning the installation is another pitfall that can lead to headaches or extra costs. Whether you intend to place a unit indoors or build an outdoor sauna cabin, site preparation is crucial. Outdoor saunas in particular need a level, solid base — remember that a fully assembled sauna with several people inside can weigh well over 500 kg. You don't want it just sitting on the ground. A deck or concrete patio that can carry the weight is ideal, and if you have to place it on the ground, use concrete pavers or gravel underneath to prevent the structure sinking or shifting.

Deck built for a Saunamo customer

Choose the location with practicality in mind: think about ease of access (a conveniently located sauna gets used more), privacy from neighbours and proximity to amenities like a shower or a power source for the heater. If outdoors, also think about weather exposure — you may need a cover or roof overhang to protect the sauna from heavy rain or snow. In those cases, weather-resistant wood (as mentioned in mistake #3) becomes even more important for longevity.

For indoor saunas, make sure the room can handle the heat and humidity (good ventilation is essential, as discussed earlier) and that the floor can support the sauna's weight. Plan the electrical work in advance: many newcomers underestimate the wiring needs of a sauna. Failing to estimate electrical requirements is in fact considered one of the top mistakes in buying a sauna. If you're buying an electric heater, check whether it needs a special high-voltage line or a circuit of a specific amperage. Hiring a licensed electrician to install the circuit and connect the heater is usually the safest option — this is not the moment for DIY if you don't have experience, since faulty electrical work can be dangerous.

Speaking of DIY, be realistic about your assembly and installation skills. While some sauna kits are designed for owner assembly, attempting a DIY installation without the right skills or help can be risky and lead to a poor setup or voided warranties. Don't be afraid to hire professional installers to make sure everything is fitted correctly, from wall panels to heater connections. Paying for expert installation can save you a lot of trouble down the line. Finally, check whether any building codes or permits apply — in some areas, larger outdoor structures or wood-burning heaters may require approval. By planning the installation details (foundation, power, ventilation, permits) in advance, you'll avoid unwelcome surprises and be relaxing in your new sauna far sooner.

Conclusion and next steps

Buying a sauna is a significant investment in your health and your home wellbeing. The good news: every one of these mistakes is fully avoidable with a little foresight and guidance. By choosing the right size, ensuring proper ventilation, investing in quality materials, selecting the right type of sauna and heater, and planning the installation, you set yourself up for sauna success.

If you're not sure about any step, don't hesitate to ask for advice — at Saunamo, we take pride in helping new sauna owners make informed choices. With expert guidance and high-quality sauna options, we're here to make sure your sauna-buying journey is smooth and rewarding.

Send us a message and one of our sauna specialists will give you a complimentary technical consultation on the best setup for you.

Avoid the common pitfalls and you'll soon be stepping into the perfect sauna, knowing you made the best decision. Happy shopping, and enjoy the heat.

Explore our products

If you're considering sauna therapy for cardiovascular benefits, infrared saunas offer sessions at gentler temperatures — ideal for regular use.

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