An open deck on the same 9'3" x 9'3" footprint as the sauna. A base frame of wooden beams, built the same way as the cabin frame, with a wooden floor made of elements laid over it.
It attaches to any TAIVE outdoor unit — the sauna, the lounge, or the pergola — so the space between and around them is finished rather than left as ground.
Ships flat-packed alongside the sauna.