I recently saw an online article where a homeowner/contractor added onto his house, but unfortunately, he had to excavate out from under one exterior wall's footing, pour a larger footing under the existing one, allowing him to make that wall part of a 2 story addition.
Question for the experts: Is this a fairly common/difficult process? My house is small, but I am pondering an addition, building onto one side where I'm sure the footing only supports just a single story. I could build a separate structure, pouring a foundation then bridging the two structures, but I'm not sure that the cost would warrant the extra work.
Any thoughts on this would be greatly appreciated.