In modern construction, the buildings have to be independent of each other, a builder can’t take a short cut and lean a new building against an old one as was done in the days before strict construction codes and inspections. In essence, the walls abutted to another building are not load bearing, and are anchored a small distance a Way so as to allow for expansion and contraction of materials. Buildings that are put up at the same time can be of one complete construction with differing exteriors to give an appearance of being separate.