Adding a foundation under a 1 story addition on 2 story house

[Elliot]

I am working in CA16. I finished drawing a 1 story  house with a full basement. I set the foundation defaults as 8" concrete stemwall 96" tall with footing and a 4" slab for a floor.  It worked fine on the house. Then I drew a single story addition on the rear of the house for a master suite.  But it did not draw a foundation. How do I get chief to draw the correct foundation just under the new addition totally different from the rest of the house.  This area needs to be 24" stemwall with footing and no slab. thanks folks!!

[GeneDavis]

On floor level 0, with the reference floor showing floor 1 above, draw foundation walls, the frostwalls ("foundation walls") you want under the bedroom addition walls, where needed.  

 

Now go to level 1 and open the addition room and edit its structure appropriately, specifying that this foundation "room" supplies floor for the room above.  Edit the absolute elevation of the floor level to what you want.  I have presumed your "addition" has a slab floor structure. 

 

A section through things at this point might look something like what is shown in the pic, below.  Now you gotta figure out what to do at the interface.