What humidity problems can cause a home sauna in the basement?
The use of a home sauna in the basement changes the indoor climate and leads to an increase in room temperature. Warm air can absorb more moisture than cold air. This can quickly create a problem in cool basement rooms due to condensing moisture. This applies not only to one room, but to the entire basement. Temporarily raising the room temperature to 20 degrees will bind 350 grams of water per 20 cubic meters. At 25 degrees, it is 460 grams. However, at a room temperature of 10 degrees, only 190 grams are bound. This means that large amounts of moisture are released when the basement cools back down.
How mold develops
Without ventilation and insulation, high humidity levels quickly lead to mold growth. Cool surrounding building components, such as ceilings, walls and floors, cause the air to cool and release moisture. If this is not controlled by heating and ventilation, moisture penetrates plaster surfaces, which in turn causes mold and rot. In addition, plaster spalling and salt efflorescence occur. The consequences are damage to the building fabric and high costs for remediation.
What can be done about moisture and mold in the basement?
In order to operate a home sauna without the aforementioned undesirable side effects, it is necessary to provide thermal insulation and effective ventilation in the basement. Not only the walls, but also ceilings and floors should be included in the insulation. On the room side, an airtight vapor barrier must be installed prior to thermal insulation to prevent moisture from penetrating the insulation material. Calcium silicate boards, insulation boards made of mineral foam or special PUR boards are recommended as insulation materials.
What should the floor be like?
To prevent mold and moisture damage, a suitable floor should be installed in the basement. It is especially important to apply a vapor barrier to the screed. Polystyrene boards 10 centimeters thick can be laid floating on the special film. Alternatively, polyurethane foam boards can be used, in which case the required insulation thickness is reduced to six centimeters. Make sure to use pressure-resistant material.
Drywall screed elements can be used as support elements for the actual floor. Tiles can then be laid on them. Note that the thermal insulation measures raise the level of the basement floor by 10 to 14 centimeters. Also, due to the thermal insulation of the walls, you need to take into account a certain loss of space.
The right ventilation for the basement
To regulate humidity in the basement, not only insulation, but also good ventilation is necessary. For this purpose, a dehumidifier is not enough. Rather, it must be ensured that the hot and humid sauna air is removed and cool and dry air is supplied from the outside. This works best with cross ventilation. If possible, additional windows and openings should be created. Alternatively, fans can be installed. However, this only makes sense if not only the inside air is removed, but also fresh air is supplied by the fan.
Control the humidity
The ideal value for humidity in the basement room is 55 percent. You can check the value with a hygrometer, which you can buy by mail order. They are available as pointer instruments or digital devices.
Conclusion
Using a home sauna in the basement can cause moisture problems that can lead to mold growth and other damage to the building structure. The rise in room temperature and release of moisture in cool basements can cause condensation and moisture penetration. To avoid these problems, effective thermal insulation and ventilation of the basement is required. An airtight vapor barrier, appropriate insulation materials, and a vapor retarder on the floor can help reduce moisture problems.
In addition, good ventilation is needed to remove hot, humid sauna air and supply fresh, dry air. Humidity control with a hygrometer is also recommended to achieve the ideal humidity level of 55 percent in the basement. With these measures, a home sauna can be operated in the basement without humidity problems.
