Sauna plans to start with

Here are some designs my brothers and I worked on several years ago when we were building saunas.

Space a few 4x4 posts on the ground and screw two 3/4” treated plywood sheets on top for a floor. The bottom of your wall should be a treated 2x4, but the rest all regular 2x4s.

The inside finished height of your ceiling should be as low as 7’ unless you need more clearance over a wood-fired heater.