Lots of sims sweating together. Cozy!
Not medieval, but if you have a modern save and want a cozy sauna, use these!
Uses the textures from EA standard sauna.
(Picture shows medieval version, but the build should look basically the same.)
Build the sauna like this:
You build your sauna like this: make a room 4x2 squares (or 4x4, 4x6 ect, depending on how long sauna and how many seats you wish to have). Place the lower benches in a row. Then the upper benches “on top. You dont need a fireplace, the steam will come from the floor, but a nice fireplace of course gives even more cozy.
If you want a very small sauna, in a small house perhaps, you can use only the lower benches and make one thats in 3x2 squares.