There are hundreds of items in each project to consider so a ball-park figure looks at more than just square feet. For example, a basement will cost more if you have a bathroom, wine room, bar and/or kitchen. A remodel might only be a refresher of a bathroom or a full house overhaul. An Addition could be just adding a main level bedroom out the back or making a single story bungalow into a 2-story home. New builds mostly consider the materials and products going into the home, like GE vs Maggenau appliances, granite vs marble, single story vs 2 story, and traditional vs contemporary.