Heating a wood-fired sauna
A wood-fired sauna offers a traditional Finnish sauna experience. To ensure a safe and enjoyable session, it’s important to understand the proper heating methods. While many Finns are familiar with heating a sauna, not everyone gets to enjoy the unique heat of a wood-burning stove. In this guide, we walk you through each step of how to heat a wood-fired sauna properly.
All Suomen Kotteria rental cottages are equipped with at least one wood-fired sauna included in the rental price. In addition to the cottage saunas, two of our villas in Pyhtää offer separate shoreline saunas. The Struka rental villa features a riverside sauna, while the Skitunäs villa includes a spacious seaside sauna. These can be reserved by guests staying at the respective cottages.
1. Preparing the sauna
Before starting the fire, make sure you have all necessary tools and materials.
The firewood should be as dry as possible—ideally split during the previous summer or earlier—since wet wood burns poorly and produces more smoke and particle emissions. All Kotteria cottages provide machine-dried birch firewood in bags. You can split smaller pieces from these logs to use as kindling.
For starting the fire, you’ll need some kindling, such as birch bark, firelighters, or newspaper. Birch bark is typically available at the cottages, but if you prefer firelighters, please bring your own. For example, the ABC service station in Pyhtää sells firelighters. Please note: using flammable liquids in Kotteria’s sauna stoves is strictly forbidden.
You’ll also need matches or a lighter, a sauna bucket and ladle, and a separate water bucket to fill the sauna bucket.
2. Checking the sauna’s condition and safety
Ash Box
Before heating the sauna, empty the ash box into a separate metal ash bucket. Make sure the ashes have fully cooled before disposing of them.
Ventilation
Proper ventilation is essential for both comfort and safety. Check that the air intake and exhaust vents are open and functioning. This ensures fresh air circulation and helps maintain optimal burning conditions.
Chimney and Flue Damper
Ensure the chimney is clean and unobstructed. The flue damper must be fully open before lighting the fire. Cold weather, water accumulation, or long periods of disuse can cause poor draft. If the chimney doesn’t draw smoke properly, it may back up into the sauna room. Always confirm that the chimney is drawing air effectively before starting a fire.
3. Lighting the fire
Placing the Firewood
Stack small kindling and dry wood in the firebox with enough space between logs for airflow. Use birch bark, fire starters, or dry newspaper (uncoated paper only) as kindling. Traditionally, Finns place kindling under the wood and light from below. However, lighting from the top is more environmentally friendly—it helps gases burn more completely and reduces emissions.
Igniting the Fire
Once the fire is lit and the wood begins to catch, close the firebox door and open the ash drawer slightly to increase airflow. If the firebox door has air vents, open them as well. This oxygen boost helps the fire burn efficiently. When the fire is burning steadily, you can reduce airflow by adjusting the vents and closing the ash drawer nearly all the way.
4. Adding firewood and maintaining the fire
Add More Firewood
Once the initial batch of wood is burning well, add larger logs gradually. Place them carefully so as not to smother the flames.
Airflow Control
Adjust the ash drawer and air vents to ensure a steady burn. Too much air causes the wood to burn too quickly; too little, and the fire may smolder.
Monitoring Temperature
Ideal sauna temperatures range from 70°C to 80°C (160°F to 175°F). Depending on the size of the sauna and outside temperatures, heating may take around 30–45 minutes.
Maintaining the Fire
Add firewood as needed during the heating process. Avoid overloading the firebox to maintain even heat and prevent overheating.
Heating the Stones
Allow the sauna stones to heat thoroughly before throwing water on them for steam. Hot stones produce soft and pleasant steam. For the best experience, burn two to three full loads of wood, let the fire die down to glowing embers, and enjoy your sauna in the residual heat. This method works especially well with heavy stone-mass heaters.
5. Enjoying the sauna and traditional saunarituals
Sauna as a Holistic Experience
A wood-heated sauna is more than just warmth—it’s a ritual of relaxation and tranquility. Saunas can improve circulation, relieve muscle tension, and support recovery after physical activity. Alternating hot and cold exposure strengthens the immune system and may help with respiratory symptoms. Sweating aids in detoxification and promotes clear skin.
To learn more about sauna health benefits, read our blog: “The Lakeside Sauna Invites You to Unwind.”
Cooling off and swimming
A key part of Finnish sauna culture is cooling off between rounds of steam. At Kotteria cottages, you can step outside to refresh in the open air or take a dip in the nearby sea or river, depending on your location. This contrast of heat and cold is invigorating and deepens the relaxation effect. Our lakeside and seaside saunas offer a unique combination of nature, tradition, and well-being.
The birch whisk (vihta or vasta) tradition
Whisking with a birch bundle is an ancient Finnish sauna tradition symbolizing cleansing and renewal. It not only stimulates the skin and improves blood circulation but also carries cultural meaning, often associated with celebration and spiritual refreshment. Making or using a fresh vihta enhances the authentic sauna experience—something every sauna lover should try at least once.
Whisking with birch twigs (vihtominen)
A vihta (also known as vasta) is traditionally made in early summer, when birch leaves are lush, vibrant, and release a fresh, invigorating scent. Making a proper vihta is a craft of its own. Birch twigs are carefully bound into a tight bundle to ensure they stay intact during the sauna session.
When the sauna is hot and the steam feels pleasant, the vihta is soaked in cool water. This softens the twigs and enhances the release of the birch’s natural aroma, which fills the sauna with a refreshing forest scent. Whisking means gently tapping or brushing the body with the vihta. This stimulates blood circulation, relaxes muscles, and adds a therapeutic layer to the sauna experience.
Whisking offers several health benefits. It improves circulation and opens the skin’s pores, helping the body detoxify through sweat. The rhythmic tapping eases muscle tension, reduces soreness, and supports recovery after physical activity.
The birch leaves also release essential oils with soothing properties that may help open the airways and ease breathing, especially during the cold season. Combined with the sauna’s heat, the physical stimulation from whisking promotes deep relaxation and helps reduce stress.
6. After the sauna
Let the fire burn out naturally: Once your sauna session is over, you can add a small final batch of firewood and let it burn down gently. This helps dry the moist wooden surfaces after use.
Closing the damper: Only close the chimney damper once the embers have turned completely black. If you’re leaving the cottage, you can leave the damper slightly open—this allows air to circulate through the chimney and keeps it drier, preventing moisture buildup.
Ash removal: Once the stove has completely cooled, remove the ashes and transfer them to a metal ash container. Keep in mind that ashes can retain heat for more than a day, so always handle them with care.
Clean the sauna: Sweep the floor and remove any birch leaves left behind from whisking. Leave the sauna clean and tidy for the next guests.
Experience authentic relaxation
Come and unwind in the wood-fired saunas of Kotteria rental cottages! After a proper sauna session, your body feels light, your muscles are relaxed, and your mind is clear. Whether you’re enjoying the peaceful heat of a cottage sauna or a scenic moment by the shore in one of our separate lakeside or seaside saunas, the traditional Finnish sauna experience is sure to leave you feeling refreshed and renewed.
Suomen Kotteria Oy, Rental villas in Southern Finland, +358400868889, asiakaspalvelu@kotteria.com