What an ADU
actually costs
in San Diego.
Every other builder in this county will tell you it depends. It does — but not on everything, and not by as much as the evasion implies. Here are our three numbers, and an honest account of what sits outside them.
Reviewed August 2026 · [TODO] re-check quarterly
The three numbers
We build three plans and nothing else, which is the only reason we can put a figure on a web page at all. A builder doing bespoke work genuinely cannot — every project is its own estimate. Ours have been drawn, priced and built before.
The range across all three, from the smallest at its plainest to the largest at its best, is $299,000 to $585,000 for the building.
| Plan | Standard | Select | Signature |
|---|---|---|---|
| CADU 500Studio · 500 sq ft | $299,000 | $329,000 | $359,000 |
| CADU 7501 bed · 1 bath · 750 sq ft | $365,000 | $399,000 | $439,000 |
| CADU 12002 bed · 2.5 bath · 1,200 sq ft | $475,000 | $525,000 | $585,000 |
Finish level is chosen per category, so most builds land between these columns rather than on one. Price yours in the studio.
What the number includes
The building, finished and inspected: foundation, framing, envelope, roof, windows and doors, insulation, drywall, the full electrical and plumbing package, HVAC, the kitchen and bath at the level you chose, flooring, paint, fixtures, and the drawings and Title 24 calculations that get it through plan check. It also includes us running the permit application and answering plan-check comments.
What sits outside it — and why that is where the variance lives
Site work. This is the honest part, and it is the reason a headline price alone is not a quote. On a flat lot with the panel close by and the sewer where you would hope, site work is modest. On a canyon lot in Del Cerro with a 1962 main panel and a long sewer run, it is not.
- Utility trenching and connections — distance from the main house to the new unit is the driver.
- Sewer or septic tie-in — and whether the existing lateral has the capacity.
- Panel upgrade — most homes built before the 1980s need one to carry a second dwelling.
- Grading, drainage and access — the item that moves most on a sloped San Diego lot.
- City fees — parcel-specific, see below.
We put a number on all of it in writing after the site walk, as a fixed scope with named allowances. Until someone has stood on your lot, any builder quoting you a total is guessing.
The San Diego-specific items
Impact fees. An ADU under 750 sq ft is exempt from development impact fees under state law — which is a real part of why the CADU 500 is priced where it is. Above that threshold the fees are charged in proportion to the primary dwelling. We do not print a fee figure because San Diego does not publish a flat one; it comes out of the city's parcel-specific calculator. Treat any site quoting you a confident dollar amount with suspicion.
Coastal. If your lot is in the Coastal Overlay Zone, a detached ADU needs a Coastal Development Permit. You will read elsewhere that you are exempt beyond fifty feet from the bluff — that threshold belongs to a different exemption, and the municipal code carves ADUs out of it. Budget the time.
Fire zones. In a Very High Fire Hazard Severity Zone the building has to meet the wildland-urban interface standards, a four-foot side and rear setback applies regardless of height, and bonus-programme units need sprinklers. All of it is buildable; it costs more, and we would rather say so before you fall for the plan than after.
Why nobody else publishes a price
Two reasons, one fair and one less so. The fair one: a custom builder genuinely cannot, because there is no repeatable unit to price. The less fair one: a number on a page can be compared, and a consultation cannot. We would rather be compared. If our figure is higher than someone else's, you will find out in ten seconds rather than after three weeks of meetings.
Price your own build — pick a plan, pick a level for each finish, and watch the figure move.
Open the studio