So, the planks have been laminated and the edges trimmed (you can see on the wall a plank before being rectified)
The tongue and grove joint is hand made with a handsaw and chisel. To see the process and understand the way the japanese ofuro water-tightness is assured, refer to the second video from the top in our media section
3 faces have been assembled together. Now is time to insert the bottom plank. Finally, the last wall will be hand-planed on both sides before being set in place and close the circle.
You can see here the geometry of the traditional “Tjoint”
To tighten up the faces, we use long stainless steel bolts. The head of the bolts is capped with round wooden dowels (for a natural look) or copper plates (the traditional detail of the Edo area, borrowed from the ship building practices).