Firstly, it's important to choose the right type of stones. Many people prefer to use granite stones due to their durability and heat resistance. Others prefer basalt stones because of their high thermal conductivity and ability to hold heat for a long time.

But the most important thing is not actually which type of stones you choose, but rather their size. A common recommendation is to use stones that are approximately the size of a fist. This is because smaller stones can quickly become too hot and damage the sauna heater, while larger stones can take longer to heat up and provide uneven heat in the sauna.

But what stones should you avoid in the sauna? A common mistake is to use stones that are treated with chemicals or that contain minerals that can release gases at high temperatures. This can cause irritation to the eyes and airways and can be dangerous for people with asthma or other breathing problems.

Therefore, it's important to use clean and unpolished stones that don't contain any dangerous chemicals or minerals. It's also a good idea to wash the stones thoroughly before using them to remove any dirt or dust.

Another thing to consider is the amount of stones you use in the sauna heater. Having too many stones can cause the sauna to become too hot and uncomfortable, while too few stones can result in the sauna not becoming hot enough.

"A good rule of thumb is to use about 1 kg of stones per cubic meter of sauna space. This provides a consistent and comfortable heat in the sauna while not becoming too hot."

So what is the best combination of stones to use in the sauna? It's really up to personal preferences, but a common combination is to use a mix of basalt and granite stones in roughly equal sizes.

Basalt stones provide high thermal conductivity and hold heat for a long time, while granite stones provide even and comfortable heat. Combining these two types of stones provides an effective and comfortable sauna experience.

Finally, it's important to remember to choose high-quality stones that are natural and not artificial. Artificial stones can contain dangerous chemicals and can break down at high temperatures, which can damage the sauna heater.

So, in summary, when choosing stones for your sauna heater, it's important to choose the right type of stones and ensure that they are clean and unpolished. The size of the stones is also important for providing even and comfortable heat in the sauna. Using a combination of basalt and granite stones is a common recommendation for an effective and comfortable sauna experience.


There is no specific schedule for replacing sauna stones as it depends on how often and how long the sauna is used. But there are some signs that may indicate it's time to replace the stones.

One indication that stones need to be replaced is if they have become cracked or damaged in any way. Damaged stones can further crack at high temperatures and cause damage to the sauna unit or, in worst-case scenarios, pose a danger to the user. Therefore, it's important to regularly inspect the stones and replace those that are damaged.

Another indication that it's time to replace the stones is if they have become too heavy or too light relative to their original weight. This can affect their ability to store and emit heat effectively, which can negatively impact the sauna experience.

It's also a good idea to replace the stones if they have become dirty or have a bad smell. Stones can absorb moisture and sweat from users, which can cause a bad smell and even mold growth. Regularly replacing the stones can help avoid such problems.

Generally, it's recommended to replace sauna stones every 1-2 years if the sauna is used regularly. But this is just a guideline, and it's important to make your own judgment based on your usage and to inspect the stones regularly to see if they need to be replaced.

It's also important to remember that replacing sauna stones is not a difficult process and can be done by most people with basic sauna knowledge. But if you're unsure how to replace the stones or have any questions or concerns, it's always best to seek advice from a professional.

But remember, the best stone in the sauna is the one that you enjoy and that provides you with the relaxation and enjoyment that you seek. So choose stones that suit your personal preferences and enjoy your sauna experience!

Here you can read more about how to build a sauna

Written by Martin.

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