Asbestos in the sauna: stove board, flue or tile adhesive?

In a sauna, asbestos is most likely to be found in the protective boards behind and above the stove, in the penetrations and connections around the flue of a wood-burning stove, in the seals of old stoves and fireplaces, and in the tile adhesive, grout and filler of the steam room and washroom, if the sauna was built or renovated before 1994. The wooden panelling and benches are not asbestos, but there may be an old board behind the panelling. Asbestos cannot be identified by eye, so any suspect material is analysed in a laboratory before you replace the stove or renovate the sauna.

This article goes through the typical places for asbestos in a sauna, from the steam room to the changing room, the sauna renovations where it comes up, how to take a sample safely near the stove, and what the result means for installing a new stove.

Which parts of a sauna can contain asbestos?

Protective boards around the stove

A hard board is often fitted behind, beside and above the stove as fire protection. In old saunas that board may be asbestos cement. It can be visible, painted, or hidden under panelling, sheet metal or tiles. Do not scrape, sand or drill it before you know what it contains. Boards in general are covered in the article asbestos cement and fibre cement boards and fire protection in the article asbestos in fire protection.

Flue and penetrations of a wood-burning stove

In a wood-heated sauna, the things to test are the flue pipe and chimney, the penetrations through the ceiling and wall, and the seals and sealing compounds at the flue connection. There is often a protective board around the penetrations, and old connections may have been sealed with asbestos-containing rope or sealing compound. If the flue pipe or part of the chimney is made of a hard, grey, cement-like material rather than metal, test that too.

Stove and door seals

The door seal ropes of old wood-burning and masonry stoves, the ash door seals and the jointing compounds in the masonry can contain asbestos. Fireplaces and stoves are covered more broadly in the article asbestos in fireplaces and stoves.

Electric sauna stove

With an electric stove, the things to test are usually around it: the protective boards, the wall layers and the mounting points. An old stove should not be taken apart; it is removed in one piece. Disconnecting and connecting an electric sauna stove is a job for a qualified electrician.

Steam room floor and lower walls

The floor tiling, tile adhesive and fillers in the steam room, as well as tiling on the lower part of the walls, are the same materials as in a bathroom. Under old tiles there may also be adhesive from an earlier floor covering.

Washroom and changing room

Tile adhesive, grout and fillers in the washroom are tested the same way as in a bathroom, and they are covered in the article asbestos in the bathroom. In the changing room, test the vinyl flooring with its adhesive and the wall fillers.

Where is the sauna?

• A sauna in a detached house has often been renovated at the same time as the bathroom, so the tiling and fillers are the same age as that renovation. In a basement sauna the stove may originally have been wood-fired, in which case the old flue connection may still be in the structure.
• The shared sauna in an apartment building belongs to the housing company, and the company decides on its renovation. In a sauna inside a flat, the surfaces, benches and stove are usually the shareholder’s maintenance responsibility and the waterproofing is the housing company’s, so the renovation is reported to the company in advance. See asbestos in apartment buildings.
• A lakeside or garden sauna is often the oldest and most self-repaired building on a cottage plot. Test the roof, wall boards and flue at the same time. See asbestos in a summer cottage.

Which sauna renovations bring up asbestos?

• Replacing the stove: a new stove may need different mounting or protection from the old one, which means drilling into the protective board or removing it. Test the board first.
• Switching from a wood-burning to an electric stove: the old flue connection and penetration are removed or sealed, so their seals and boards are tested.
• Replacing the panelling: when old panelling comes off, a board may be revealed behind it, which is tested before removal.
• Renewing the tiling: floor and wall tile adhesive and fillers are tested before chiselling.
• Replacing the benches: the benches are wood, but if new fixings are drilled into a wall board, the board is tested first.

How do you take an asbestos sample in a sauna?

1. Let the stove cool down completely and make sure an electric stove is switched off.
2. Wear disposable gloves and a respirator of at least class FFP3.
3. Find an edge or corner of the board that you can reach. If the board is behind panelling, carefully remove one panel board next to the stove.
4. Lightly mist the sampling spot with a spray bottle to keep dust to a minimum.
5. Snap off a small piece of about 2–5 centimetres from the edge of the board with pliers. Do not saw or drill. From a seal, a piece from the end of the rope is enough, and from tiling, remove a piece of adhesive and filler down to the substrate.
6. Drop the piece into a zip-lock bag, seal it and put it inside a second bag.
7. Mark the bag with the location, for example "sauna, board behind stove" or "sauna, ceiling board above stove".
8. Cover the sampling spot with tape and wipe the area with a damp cloth. If the spot is close to the stove, do not heat the sauna until you have the result and the spot has been repaired.

More detailed instructions are in the articles how to take an asbestos sample and protecting yourself when sampling asbestos.

What does the result mean?

Onelab analyses the sample with a JEOL SEM-EDS electron microscope in accordance with ISO 22262-1, and the result is sent by email, typically on the day the sample arrives.

• No asbestos detected: no asbestos was detected in the sample. The result applies to the tested board or material. The boards on the back wall and the ceiling above the stove may have been installed at different times, so test them separately if they look different.
• Asbestos detected: an intact board can stay in place as long as it is not drilled or broken. If installing the new stove requires removing or drilling the board, the work is planned as asbestos work and the removal is carried out by a company authorised for asbestos removal work.

If the sauna is part of a larger renovation or demolition that requires an on-site asbestos survey, the survey is carried out on site by a qualified surveyor. Onelab is a laboratory, and on-site surveys are handled by our sister brand AsbestiPro.

How much does the analysis of sauna samples cost?

The analysis costs €39.90 + VAT per sample, and the price is the same for 1–100 samples. A sauna renovation often involves a few materials, for example the stove board, the tile adhesive with its filler and a flue seal, and they can all go in the same order. Orders of more than 100 samples can be priced separately. Postage is not included. You can order the analysis online and send the samples to the laboratory by post.