Re: addition without foundation or footing
Unless you're a pretty experienced DIY'r, this isn't really a job for the weekend warrior type. If the structure is in reasonable shape, it might be able to be jacked into proper plane with the rest of the house, then excavate and pour footings/foundation. If the structure is a lost cause (excessive rot, extreme sag, etc ) then removal and rebuilding properly would be the way to go.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!