One space one taiji, both applies.
Both Ming Gua BaZhai, along with the Jiu Xing Shuifa as well as NaJia use hand in hand. Together with the external landform assessment.
If we look at the development of BaZhai, it meant for good health. In ancient times where agriculture centric, good health and many offspring relates to more people working on the plot for harvest.
Both Ming Gua and sitting are centered around the man of the house. That where the concept of house must match man was derived.