Estimate for Addition to existing house

[caiguycaiguy]

Maybe this old thread will help

Addition vs. Buy with sq footage

Got a question guys: Is it better, given the current peninsula prices of $1K/sq ft to buy the square footage already there or to add on? What’s the current price rate for doing an addition? Let’s say 1000 sq ft and needing a bathroom, but not a kitchen? Like you take a 2-1 and expand backwards adding either one or two stories and putting in a family room (on the bottom), plus two bedrooms and a bathroom (second floor). Redwood City, Inc flats or Unincorp part of RWC, flat part. How does an addition change the property taxes? How is that amount assessed? How long does an addition take?