For most of San Diego's history, adding a second dwelling unit on a residential lot required discretionary approval — a hearing, neighbor notification, a public record vote — that made the economics impossible for most homeowners. A 2017 state law began dismantling that barrier, and a series of follow-on bills in 2019, 2020, and 2022 effectively ended discretionary review for most ADU types in California. The City of San Diego now processes most ADU applications ministerially, meaning the City checks for code compliance and issues the permit — no hearing, no neighborhood vote.
What that means practically: if your lot is zoned for single-family residential, you can generally build one ADU and one Junior ADU (JADU) by right. A JADU is a converted portion of the existing house — a converted bedroom with a kitchenette, for example — capped at 500 square feet. A standard ADU has no hard size cap tied to lot size under current state law (though local height and setback limits still apply), and a detached ADU in San Diego can reach 1,200 square feet.
The three ADU types we build most often
Garage conversions are the fastest and most cost-effective path. The existing structure provides the shell; we add insulation, drywall, a kitchen and bath rough-in, HVAC, and the connections to the main home's utilities. In San Diego's mild climate, converting a two-car garage to a 400–500 square foot ADU with a full bath and kitchenette typically costs $80,000 to $110,000 and takes 4–6 months from design to certificate of occupancy.
Detached new-build ADUs — backyard cottages built from the foundation up — are the most flexible option and typically rent for the most. They run $120,000 to $180,000 for a 600–800 square foot unit with one bedroom and full kitchen. Build time is 8–12 months. The permit process for a detached ADU in San Diego is now fully ministerial for lots that meet setback requirements, which most single-family lots do.
Attached ADUs — additions to the existing home's footprint — follow standard addition rules plus ADU-specific review, which makes them the most complex permitting path. We build fewer of these but they make sense on lots where setbacks preclude a detached structure.
The San Diego rent math
Current San Diego ADU rents: a studio garage conversion in North Park or Hillcrest rents for $1,600–$2,000 per month. A one-bedroom detached ADU in La Jolla or Pacific Beach reaches $2,400–$3,200. At those rents, a $100,000 garage conversion pays for itself in financing costs in roughly 8–10 years while appreciating the property. That math explains why ADU permits in San Diego County have roughly tripled since 2019.
One caution worth stating plainly: the ADU laws removed the discretionary barrier, but they did not remove the building code. Structural, electrical, plumbing, and energy-code requirements all apply — including California's Title 24 energy standards, which for ADUs built after 2020 require solar-ready panels and in some cases solar itself. Any contractor offering ADU permits at suspiciously low costs is either skipping inspections or building below code. We permit everything.