How to deal with the level difference of the two parts in a single building

Hello everyone.

My target building is divided into two parts because of their different levels, but there is a ground floor can never be generated when I use “Mass2Zones”. Is there anyone can help me to solve this problem? Thanks in advance.

Roy (522 KB)

Yi, you forgot to internalise brep.

The floor is generated but it’s not a ground floor. check the output for exposedFloors.