For an apartment building I work with spaces to determine the area of each apartment. My client would like to have the netto area of each apartment, without the area occupied by the shaft.   I drew the outer walls of the apartments, and a wall around each shaft. Then with Inner Boundary mode selected, I create the spaces. Works fine. But after a while the reference point of the space moves to inside the shaft and the area of the apartments is displayed incorrectly, because it now shows