I'm considering an addition to my building that will run right up to the property line. The building is in a commercial core of the town and I've already confirmed with bldg. dept. and town planner that I'm permitted to do this. But is it advisable to do so? Should I expect extra costs and complications, compared to a building footprint that has a set-back? The addition will require a minimum 4'ft deep foundation and will be 2 storeys high in about 1/3 of the structure and 1 storey for the remaining.