Until then the smallest teahouse had a space of 4 and a half tatami mats, but Rikyu made it smaller reducing the number of mats to 3 or even 2, which was only common among the townsmen at that time, invented Nijiri-guchi (a small entrance to the teahouse), Shitaji window, a mud wall and an alcove 120 to 150cm in width.
それまでは4畳半を最小としていた茶室に、庶民の間でしか行われていなかった3畳、2畳の茶室を採りいれ、躙り口（潜り）や下地窓、土壁、五（四）尺床などを工夫した。