What Drives the Cost of an ADU in San Diego?
If you have searched for ADU pricing, you have seen numbers all over the map. That is because an accessory dwelling unit is not one product — it is a small home, and its cost depends on real variables.
The factors that matter most
Size and layout. A 1-bedroom ADU and a 4-bedroom ADU are different projects. More square feet means more of everything: foundation, framing, finishes.
Site conditions. A flat lot with easy access costs less to build on than a sloped lot or one with difficult access for equipment. Utility connections — water, sewer, electrical — vary by property.
Finishes and fixtures. Like any home, the choices you make inside move the budget: flooring, cabinetry, appliances, tile.
Permits and fees. Every California city has its own fee schedule and process. Permit-ready plans help, but fees themselves are set by the jurisdiction.
How to get an honest number
The only way to know what your ADU will cost is a site-specific quote. Anyone giving you a firm price without seeing your property is guessing.
Start with a free consultation: walk through your goals, your lot, and the models that fit. Then you get numbers tied to your reality — not a national average.