DIY Interior Finishing of a Sauna

As a rule, today the interior finishing of a sauna is performed by almost any construction company, but the cost of such work is quite high, so not everyone can afford to pay craftsmen for their labor. Expensive materials and painstaking work can be avoided by doing everything yourself, which allows you to save a lot. The main thing is to familiarize yourself with the finishing technology in advance and to choose the right material, making sure it is of good quality.

Initially, it is necessary to understand that the interior finishing of a sauna must simultaneously solve several tasks. The main ones are:

1. Waterproofing and insulation.
2. Extending the service life of the structure.
3. Protecting users from burns that can occur when touching heated wall surfaces.
4. Health‑beneficial properties of the materials. When exposed to high temperatures, wood releases therapeutic aromas that help alleviate various ailments.
5. Decorative role.

For the finishing to perform all these functions, the material must be selected correctly. Otherwise, after some time the craftsman will have to redo the work, again paying for consumables.

Choosing Materials

Selecting materials for interior finishing is one of the key stages. The durability of the sauna interior depends on the correctness of the final decision. The chosen finish must meet the following requirements:

1. Resistance to high temperatures – the most important rule. Failure to meet it will cause the material to deteriorate after the first use of the sauna.
2. Hygienic properties.
3. Non‑toxicity. No harmful substances should be emitted when hot air passes over the material.
4. Safety. Contact with human skin must not result in burns.
5. Attractive appearance and pleasant colour.

The ideal option is wood, which possesses all the listed properties. In addition, it can both release and absorb moisture when necessary. Wood is also famous for its unique aroma and characteristics. The key is to choose high‑quality tongue‑and‑groove boards. If the material is overly dried and not allowed to acclimatize before installation, the steam room will cause it to swell after the first uses, as it absorbs moisture and expands significantly. Conversely, using raw boards may lead to noticeable gaps after they dry.

Which Wood to Choose?

When discussing the finishing of a traditional Russian sauna with intense heat and abundant steam, it is best to opt for hardwood species. Larch, aspen, linden, and poplar are excellent choices. Their advantage is that such wood does not exude resin, does not overheat, has antifungal properties, and dries quickly during ventilation.

Often, ash is used for lining the steam room; it belongs to durable, strong species resistant to rot, and its core has an attractive appearance. As a rule, alder can be used for DIY interior sauna finishing. This sturdy, odorless wood with a uniform structure is ideal for constructions made of foam blocks or other fragile building materials. The main plus of alder is its inability to absorb foreign odors; it also has a distinctive light‑brown colour with a pinkish tint. Abroad, alder is the most commonly used wood for this purpose.

Which Material to Use for the Washing Area?

Coniferous woods should not be used for the steam room itself. For example, pine heats up strongly, making it uncomfortable to touch during a bath, although it can be used for the vestibule or relaxation room where the temperature is lower. In these spaces the pine aroma is pleasant and may help treat various infectious diseases. Experienced sauna‑goers also praise moisture‑resistant spruce tongue‑and‑groove panels with a pleasant orange hue.

A more expensive option is oak. This wood is highly durable, but it is unsuitable for interior sauna work because, under high temperatures, it becomes so pliable that it can be bent into various shapes. Oak, however, is resistant to rot.

Technology

The interior finishing of a sauna is carried out in stages. If you follow the instructions, you can quickly and easily line a room of any size. The process can be divided into the following steps:

1. Acclimatize the material. Place the wood inside the sauna and leave it there for at least 24 hours.
2. Make a lath framework. Use strips with a cross‑section of 5 × 5 cm. The distance between parallel strips should be 50 cm.
3. Install thermal and vapor barriers over the laths.
4. Mount wooden panels. They can be installed vertically, horizontally, diagonally – as you prefer.

For fastening, use copper or bronze nails that will not rust after the first use of the steam room. The mounting method is simple: each subsequent panel is inserted into the groove of the previous one. Floors can be covered with ceramic tiles or again with hardwood boards. Oak, known for its wear resistance, can be used, but such a surface is quite slippery.

Some sauna owners leave the floors concrete, installing a “warm floor” system under the screed. This setup can be used only in the vestibule or relaxation room; interior sauna finishing with heated floors is prohibited because of the high humidity.