Sep 8, 2026
What an addition really costs in the north suburbs
The square-foot number you see online leaves out three things that always show up.
Foundations. An addition needs its own footings, and on clay soil that is deeper and pricier than people expect.
The furnace. Adding rooms usually means the existing system can no longer keep up, so budget for a second zone.
Permits and drawings. In most villages here that is four to seven thousand before anybody digs.