After insulating, the poplar planks serve as the covering for particular wall sections as well as the ceiling, laid on top of the hewn birch beams 12 x 12 cm. Once jointed a groove is routed in the edges and a 6 mm plywood spline gives the jointed planks rigidity.
The joints are more or less as they came off the axe though I knocked down some unevenness quickly with a block plane. The surfaces are as they initially came off the bandsaw mill, widths average probably 30 cm not being parallel but tapered along the length of the planks set with wide ends alternating from top to bottom.
One quirk being the batten shown in the lower center of the picture where it was not possible to insert the final plank with a spline in there. The screwed-on batten provides the rigidity in its place. Maybe I could also add the tapered shank cut nails from Glasgow Steel Nail, giving their good grip there.
