It was devised to be removable as necessary by carving each one toi (a generic term gutter) in the threshold and kamoi (a generic term for a head jamb, normally having tracks for sliding doors or partitions) and setting a sliding door by carving the gutter of kamoi deeper than that of the threshold.
敷居と鴨居にそれぞれ一本の樋（溝）を設け、鴨居の溝を敷居の溝よりも深く彫る事によって建具を落とし込み、必要に応じて取り外すことができるように工夫された。