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Frequently Asked Questions
Sauna
Sauna Care & Maintenance
Your sauna is designed for outdoor use and the wood (cedar and thermowood) we use is naturally resistant to the elements. Nonetheless, over time your sauna will naturally weather and the color and appearance of the wood will change. To help preserve the lifespan of your sauna, it is optional to treat the exterior (only) with a stain and seal product. There are many different staining products on the market, so we don't recommend a specific one over another. That said, Behr is a reputable brand and makes good products. Look for a product that offers UV protection and mildew resistance. Stain-and-seal products usually last about 5-7 years after which time you would have to reapply a new coat.
Treating your benches and floor with paraffin oil reduces the amount of sweat and dirt that can be absorbed into the wood, which increases their life span. We recommend treating new benches and floorboards before using them and reapplying the treatment once or twice a year when cleaning the sauna. Paraffin oil is especially good for thermowood saunas. Paraffin oil is colorless and odorless, but will give the wood a slightly darker ‘wet’ look after its applied. Wood surfaces must be completely dry before you start the oil treatment. Please note there is an important difference between Harvia paraffin oil vs Paraffin Lamp Oil and/or Paraffin wax . We only recommend customers use Harvia paraffin oil we sell in their saunas.
Under normal conditions, washing the interior of the sauna every 3 to 4 months will maintain cleanliness. We recommend using the Harvia Sauna Cleanser or another suitable cleaning solution for wood. Refrain from using ammonia or harsh cleaners as they can turn the wood gray.
Wash the wood with a sponge or soft bristle brush. Always brush with the grain of the wood. If dirt is embedded in the benches, you can sand them down lightly. Rinse the sauna thoroughly with water to remove the cleaning solution. Run the heater for 1 to 2 hours to dry the room.
Sauna bathing might have accumulated visible limescale stains on the surface of the heater. For stainless steel surfaces, we recommend Harvia's sauna heater cleanser, which removes limescale stains. You should re-stack your sauna stones every 6 months as the stones’ structure will change over time in high heat and the pile of stones could cause the coils to bend into each other. We recommend replacing the rocks every 12-18 months.
After you have finished each sauna session, we recommend running the heater for an additional 60 minute cycle with the door closed. This will dehumidify the room and dry out the wood. If you are using your sauna regularly (i.e., multiple times a week) and drying out the room after each session, this should largely prevent mold formation.
If you are not using your sauna regularly, run a dehumidifier and/or fan inside the sauna to keep air circulating (and empty the dehumidifier water tank regularly). Also place desiccants (e.g., a commercial desiccant such as Damp-Rid or non-commercial desiccant such as charcoal briquettes/kitty litter) on dishes and place them around the inside of the sauna.
Without a roof installed, it is normal to experience water leaking through the roof boards. The interlocking staves do not form a watertight seal. We recommend installing our asphalt roof shingles if you purchased them, or sourcing your own roofing materials locally. Some customers have installed metal roofs or cedar shingles which also look nice. For additional protection, install a roofing underlay beneath your shingles. It's normal for some water to seep into your sauna on a rainy day, especially on days when wind is blowing rain onto the side walls of your sauna. This will not harm your sauna or diminish its lifespan. After a heavy rainfall, we recommend you turn the heater on for a 1-hour cycle to dry out the room. Running the heater a couple of times a week during the wetter months will help prevent mold or mildew from developing.
Hose it off or use a low-pressure washer to remove debris and stains.
We recommend adding shingles to the roof of your sauna as they will significantly increase your sauna's longevity and water resistance.
When you use your sauna, the rocks in the sauna heater will be heated to very high temperatures and then cool back down. Over time, this heating and cooling cycle creates cracks in the rocks that will grow. Eventually, your rocks will break into smaller pieces and you may even see pieces of rock or dust come out of the bottom of your heater.
As the rocks shrink they will settle inside the heater. You may notice it looks your rocks are gradually 'sinking'. This process can push the coils out of position and into contact with one another. (See photo below)
This is an issue because if your coils come into contact with each other they will quickly burn out and need to be replaced.
We recommend that every 6 months you turn off your sauna heater at the breaker and remove all the rocks, then re-stack them so the coils are in the correct position (vertical and not touching).
Harvia also recommends that you replace out your rocks every 12 to 18 months.
Stain-and-seal products usually last about 5-7 years after which time you would have to reapply a new coat. If you’re unsure how often to reapply, talk to someone at your local building store who can give you region-specific recommendations.
A small amount of water seeping into the sauna isn’t going to hurt it and is likely due to condensation. If you notice a substantial amount of seepage, this may mean that your bands have loosened, and water is getting in around the staves.
The wood will naturally shrink during warm dry weather so cracks can appear after extended periods of warm weather. The wood will also naturally shrink with age so cracks can appear after a few years of use. Check the tension of the bands every few months so you catch problems before they start. If you notice the bands are loose, retighten them following the same process as when first installing.
If you are unable to close cracks by tightening the bands, it means you need to add more staves under the bands. When the inside and outside of the sauna are dry, take apart the top portion of it and rebuild it with additional staves.
We recommend adding shingles to the roof of your sauna as they will significantly increase your sauna's longevity and water resistance.
After you have finished each sauna session, we recommend running the heater for an additional 60 minute cycle with the door closed. This will dehumidify the room and dry out the wood. If you are using your sauna regularly (i.e., multiple times a week) and drying out the room after each session, this should largely prevent mold formation.
If you are not using your sauna regularly, run a dehumidifier and/or fan inside the sauna to keep air circulating (and empty the dehumidifier water tank regularly). Also place desiccants (e.g., a commercial desiccant such as Damp-Rid or non-commercial desiccant such as charcoal briquettes/kitty litter) on dishes and place them around the inside of the sauna.
Like any outdoor structure, mold can develop as a result of moisture getting trapped inside the sauna. This is especially true for saunas as the bathers will sweat, releasing additional moisture into the air which can be absorbed into the wood. The key to preventing mold from forming is to ensure the inside of the sauna is frequently dried out. Apart from plain water, never eat or drink anything inside your sauna.
If you see mold on the inside or outside of your sauna, this should be treated early before it has time to grow and take hold. Clean the affected area to remove the mold. The wood can be cleaned by spraying down the area with white vinegar and then scrubbing the area with a scrub brush and soapy water. If you are unable to remove the mold with vinegar and soap, try stronger cleaning agents such as 30 Seconds Outdoor Cleaner or Behr All-in-One Wood Cleaner. Rinse the sauna thoroughly with water to remove the cleaning solution. Run the heater for 1 to 2 hours to dry the room. Any rags or scrub brushes that come into contact with the mold must be disposed of. Proper protective equipment (goggles, mask, etc.) must be worn when removing mold.