Multi roof levels projects

[Frederic Courbet]

Hi, new user here. I am trying to set up a project with multiple roof levels ( existing roof at 2400 and extension roofs at 3000 ) does it needs to be done on the storeys settings ? any link to online education where to learn on to set up extension with different roof heights ? ). Many thanks, Frederic ( BFDA Australia student )  

[SenecaDesignLLC]

I have a story for each floor and ceiling, I just place roofs an the story that matches the logical construction and how I want it to display.