Building an ADU in Orinda CA

[Shervin R.]

We are thinking to build an ADU. House is on a 0.5 acre lot and has a large flat area with access from the road. we were wondering if building an ADU for our guests or to rent is a good Idea or not and how much does it cost. Greatly appreciate your input.

[Collin Chan]

@Shervin R. I have been looking at ADUs including modular and for many of them, the costs are not lower and more restrictive in terms of layout and design.  I decided to go custom and have been quoted $250-$300 a sq/ft including everything.  Most modular don't include foundation and hook ups to electrical, water, and sewage but some will so take that into consideration when looking around.  The savings is more in the time than cost though so if you want less disturbance on site since you live there, then it might be of value to you.

Based on cost, you can use rentometer to see what a 1/1 or 2/1 would rent for in your area (typical ADU floorplans although you could go larger). Then you can run some numbers and see if it makes sense.

Collin