by code my concrete footing had to be 3 ft deep, 16 in wide and 12 in thick with rebar horizontal and uprights every 4 ft for the fountdation walls.. I next formed and poured the foundation walls . In the main front door towards the street I had L shaped rebar coming out of the walls and half pointed toward the street and half toward the inside floor. that tied the driveway pad and floor to the foundation, the other 3 drive in doors, the floor floats and soil moisture made the back floor move up about 1/2 inch. I should have put in more tie rebar at all the doors.