by Procraft
Yes. A traditional sauna needs air moving through it, both while you are using it and afterwards so it dries out. Ventilation is what makes the heat feel good instead of stuffy, and it is a large part of why a sauna stays fresh for years. It is not an optional extra.
People in a hot room use up the fresh air and add moisture to it. Without air movement the sauna goes stale and heavy, and the heat feels harder to sit in. A sauna with proper airflow at the same temperature feels noticeably better. Steady air exchange is one of the differences between a sauna that people love and one that gets used twice.
The bigger reason is drying. Every session puts moisture into the room from steam and from sweat. If that moisture cannot get out, it sits in the wood. A sauna that dries fully between uses stays clean and lasts. A sauna that stays damp is the one that develops problems. This is the single most important habit in cedar sauna maintenance.
The normal approach is an inlet low down, generally near the heater, and an outlet higher up on the far side of the room. Fresh air comes in low, gets drawn up past the heater, crosses the room and leaves high. That sets up gentle circulation rather than a draft. The outlet is usually adjustable so you can control the rate.
The exact placement and sizing depends on the room and on the heater manufacturer's instructions, and it is worth following those instructions rather than a general rule, because vents that are wrongly placed can pull heat straight out or leave dead spots.
Whatever vents the sauna has, get in the practice of leaving the door open after a session so the room airs out and dries completely. It costs nothing and it is the single best thing you can do for the life of the wood.
Ventilation is far easier to get right during construction than to add later. If you are planning a sauna, sort out the vent locations at the same time as the heater position and the electrical run. See how installation works.
Procraft builds Western red cedar saunas and makes four CSA-approved electric sauna heaters from 4.5kW to 9kW. See the heaters, read about Western red cedar, or see how installation works.