Electric and Wood-Burning Saunas: Same Goal, Different Execution.

If you read enough about sauna ventilation, you’ll quickly notice something confusing: even people who care deeply about “good saunas” disagree on vent placement. That isn't because anyone is careless. It is because electric and wood-burning saunas can behave very differently. Furthermore, every setup fluctuates based on the heater, airtightness, and daily conditions like wind and air pressure. Therefore, ventilation often requires fine-tuning on-site.

Much of the current understanding about sauna ventilation comes from Trumpkin’s Notes on Building a Sauna and Lassi Liikkanen’s - The Secrets of Finnish Sauna Design book. If you are building a sauna, I strongly recommend checking them out. This post builds on that foundation, translating their principles into clear diagrams and practical suggestions for your build.

The most important distinction is simple:

• Wood-burning saunas generate airflow naturally.

• Electric saunas often need help to move air predictably.
  

Wood-burning heater diagram.

1. Fresh air enters through a periscope-shaped passive vent, with the interior opening typically located roughly 2/3 of the way between the top of the heater stones and the ceiling.

2. The incoming air is designed to mix with the rising heat from the stove as it travels toward the bathers.

3. A secondary low-level intake near the floor aims to move stale air across the floor toward the heater, supporting overall air circulation during use.

4. The wood-burning heater continuously draws air for combustion, acting as a primary driver of ventilation without mechanical assistance.

5. Situational: Additional combustion supply should be considered if the heater manufacturer requires it.

Electric heater diagram.

1. Fresh air enters through a periscope-shaped passive vent, with the interior opening typically located roughly 2/3 of the way between the top of the heater stones and the ceiling.

2. The incoming air is designed to mix with the rising heat from the heater as it is carried toward the bathers.

3. A mechanical exhaust located below the foot bench is intended to remove stale air; industry standards often suggest approximately 20–25 CFM per person, with preference given to low-noise fans.

4. Situational: In some installations, an additional passive air inlet may be necessary to help prevent high-limit sensor trips, depending on the heater manufacturer’s specifications.

Why the “periscope” shape?

In both examples, the periscope-shaped duct prevents the passive air intake from acting as an exhaust. Because warm air naturally rises, the downward leg of the duct resists reverse flow and helps ensure the opening functions as an intake.

If you want a build that incorporates these best practices, check out our Sauna Building Plans. We provide step-by-step instructions and material quantities so you can build with confidence.

Happy sauna building!