Thank you both for your input!  
The garage has the 12.5' ceilings to accomadate a lift and and 10'x10' doors so I can fit anything in the future (boat, trailer, lifted truck etc). 
  
Is there a way to adjust the overhang on individual walls?  I attempted ot by selecting the wall-open object-roof-and adjusted the overhang, but nothing changed in the 3d view