Split floor into multiple floors to allow different room-bounding selections

[HVAC-Novice]

I looked at this way to divide a floor in parts and can't do it. What i want to do is to split a floor in sections so that in some areas i can set them to room-bounding, but not in all. Structurally it is all the same floor. Except in the normal rooms i need it room-bounding, and in the staircase not room bounding. 

this project is from an architect and they modeled part of the floor as one (like in real World). I was considering just editing the boundary and create a second floor manually. but I hope there is a better way. 

Picture shows highlighted the monolithic floor. Red line represents where I want to split it apart. the bottom left corner in the staircase should NOT be room-bounding, the rest should be room-bounding. 

I tried the " create parts" and then edit a part and can't do that and don't know if that actually gives me 2  floors with separate room bounding. 

if i do this, nothing happens:

if I mark the full rectangle, it works, but nothing actually splits apart.

[barthbradley]

Convert Floor to Parts and then Divide. 

Help | Divide Parts | Autodesk

[barthbradley]

Room Bounding? Why is a Floor being Room-Bounding a concern? Serious question. 

[ToanDN]

Parts are not room bounding elements.  You will need to split the actual floor into multiple floors. Copy paste the floor in place and edit boundary. Rinse and repeat.

[barthbradley]

Why don't you just use Room Separation Lines? 

[HVAC-Novice]

Reason i need to do this is there is a huge area of floor that should be room bounding. but part of that floor also creates the stair case landings (that is how it actually was built, and modelled by the architect). the floor in this case actually is a waffle slab that had the coffers manually modelled. In the stair case I want rooms and spaces continuous and also above the floor/landing because I use spaces for lighting calculation (I use elum tools).

this project has 3 stair cases with similar issues. Here an example where part of the floor is in the staircase and if it is room-bounding, it prevents the rooms (and spaces) from touching each other. in other areas it breaks up the room above a landing (landing is a floor and the area above the landing would create a void in a room/space)

in stair cases I do a lighting calculation of all spaces combined since the light continues between the spaces. but if they don't touch each other, or have uncovered areas, that doesn't work. 

but reading the above, the dividing doesn't work for that  and my only option is to edit the boundary of the main floor (that stays room-bounding) and then adding the little floor in the stair case is my only option? 

[barthbradley]

What about Room Separation Lines and Room Limit Offset?  No "Room-Bounding" Floors (or Walls) needed.   

[HVAC-Novice]

The rooms I place outside the stair case are a bit sloppy and I rely on the floors to limit them. This project has multiple levels per level (they have a structural floor, and a raised floor, and for some reason other levels - that is how the original architect set it up). So it takes me some conscious thinking when selecting the upper limit. 

I have to edit the architectural model already (this is a 12 year old model, not an active project),, so i need to re-think my overall strategy how I handle the room separations. 

At this point in the project, I just create a new floor in the stair case.