Perfect timing. This is my prime Pelican time. As a matter of fact I am reviewing my plans now. My permit was stamped a couple weeks ago. This one is for me, and will be rented once done. It is a separate stand along building, jsut about 1200 sq'.
There are few questions before getting going. Keep in mind that all ADU are basically the same, follow state regs. but cities has the the final say so. That can throw a monkey wrench into your plan. Normally, its just more money and that usually solves everything.
Parking? You need one additional parking. It can be a long driveway. No parking space needed if your ADU is within 1/2 (or was it one mile) radius of any bus stop, public transportation stations. I hear people get away with bicycle hubs or city rentals. Clever bastards!
It has to be a certain sq' or percentage less the main house. I lucked out, and the plan checker fell asleep. Its just 200' less then the main house.
Set back has been expended as of the first of this year so when you talk to your architect, make sure he knows the new set back dimensions to build a bigger house. Its not that much more to get it closer to the property line.
An existing garage can be made into living space, but you must find out about parking. Parking requirements are a real PITA here (up in the bay area too, I bet) when it comes to building.
My suggestion (in sequence):
Meet up with architect. Size allotment, parking. Cost. Hillside?
Do some digging down at zoning and planning downtown to get some concrete info. You should know some of the basic.
Once you have the prelim. plans drawn, have contractor fine tune his numbers a bit but keep in mind that there might be more requirements after plan check. Grading and soil compaction may cost you a few bucks. Basic on the floor plan, a good contractor should get you a range on the cost of construction. After that, its up to the architect to work his magic and get you a set of stamped plans. Get with your contractor and build the house. Tell him you want to have the shell built, roofed, finish exterior, all mechanicals and drywall interior. You provide the finish work. Most contractor suck at finish work anyway, I found.
One thing, make sure you talk payment schedule with architect. When I am involved from the get go, I make sure both client and architect know that architect do not get pay in full unless he can provide approved plans. I use the same architect on 90% of my jobs, so he's trained.
I am much better at talking then typing with my fooking three left thumbs. You already noticed that. I will pm you my number. Pick my brain. Talking is free, happy to walk you through the process.
Interview contractors (personality match? Very important) and talk about rough construction numbers and some of the gotchas.