I apologize for the total noob question, but what’s the most efficient way to turn a closed set of model lines from Revit into a polycurve to be used as an outline to make floors for instance? thanks a bunch!
I haven’t and I will check it out, and I have fixed my issue in a very similar way, thanks for the info and the active support! 
I want to achieve the same but I am failing where a line is common to two floors. In that case I am getting a warning that PolyCurves may not be branching. For example in the below image, I have 7 model lines and would like to create 2 floors from them.
What would be the suggested solution in this case?