gbXML simulation model - Dynamo to generate floor from walls

Hi I am trying to find a way to automate place floors in my model.

I want to place floor with offset -25mm for external walls and 0 for internal walls :

option1 = all walls intersection so if there is many small room and lower level and big one at upper level I will have many small floors

option 2 = if option 1 too difficult maybe would be easier that I insert spaces first and then place floors?

any suggestions how to approach it?