Bench height before ceiling height
Start with where the bathers sit. The upper bench should place people in the heat, not down in the cooler lower layer. Then work backward into ceiling height, step height, and heater placement.
From the notebook
Sauna build notes for better questions.
Keep these close before you buy a kit, approve a drawing, or close up the walls. They are not a substitute for local code, manufacturer instructions, or a qualified builder. They are a way to notice the important questions earlier.
Ventilation that actually dries the room
Plan intake, exhaust, and drying airflow as a system. A sauna that feels fine during a session can still trap moisture after everyone leaves.
Heater sizing beyond cubic footage
Room volume matters, but glass, outdoor exposure, insulation, stone mass, warm-up expectations, and user style all change the real-world heater decision.
Clearances and surfaces
Respect manufacturer clearances and use heat-appropriate materials near the heater. A beautiful layout that ignores clearances is not a good layout.
Drainage, cleaning, and service access
Think about water, ash or debris, heater service, removable boards, and how the room gets cleaned. The best sauna still has to live in the real world.
The session path outside the room
Plan hooks, towels, changing, cooling, lighting, privacy, and the walk back inside. The sauna experience begins before the door and ends after the last cool-down.