Cost of adding a second story to home?

i want to add a second floor to my one-story home. the second floor is going to be a master bedroom w/ bath. i was thinking about 300-400 sq feet.

i hear there is a cost per square foot amount that homeowners and contractors use to estimate this type of work. anybody know that amount? or better yet have an estimate for this type of work?

i live in the sfbayarea.

The cost per square foot for such a project might be a ballpark, but it will vary wildly in different areas of the country.

Additionally, a specialized remodel like this one requires a complete and thorough estimate. This type of remodel can require structural changes–you'd be crushed to get an estimate, only to learn later that the real cost will be double.

Call in a couple reputable & licensed contractors. Show them what you have in mind, and tell them what your budget is. Experienced contractors can probably tell you right off the bat if your budget is reasonable for the project or not. If it's out of your budget, then neither you nor the contractor will have to waste any more time with an estimate. But, if you're in range, a detailed study of the project will pay off for you if you decide to do it.