Tommy2000GT
Golden Member
The rest of the laundry list posted by Tommy is potentially a great deal of work and money.
I have no opinion on the cost, especially without knowing the style of building and foundation requirements. I've briefly ball-parked adding about the same space to the back of my little bungalow, and I come up with 50-80K, with no new kitchen in the mix.
$320 a foot is a good deal anywhere in the Bay Area, and a steal in SF. $400 to $450 a square foot is common around here.
Yep, welcome to the Bay Area, where everything cost an arm and a leg 🙁