Seen this before elsewhere, when you don't get what you want post somewhere else, where the miracle worker is located.
if you look hard at the drawing it has numerous faults for an automated answer, stuff like lines don't intersect, no line past doors, plines with width don't line up with other lines and so on.
The simple answer Bpoly even if created is a incorrect shape.
As a 1st step convert plines with width to at least 2 lines better as an outline as end cap may help in working out a closed area.