I think you should not change the global/local method.
example for global red floor:
- floor height = 0,00
- wall begins at = 20 ft
- wall height = 9 ft
- window bottom height = 23 ft
-ceiling height (upper edge) = 30 ft
example for local red floor:
- floor height = 20 ft
- wall begins at = 0,00
- wall height = 9 ft
- window bottom height = 3 ft
-ceiling height (upper edge) = 10 ft
I didn't try now, but I guess, if you change the method, your doors and windows could be in chaos.
All wall heights are relative to their floor heights.
All wall beams are relative to their bottom wall heigt.
All window heights are relative to the floor height.
I did not check all these statements now, but I think they are correct.