Garage conversion vs detached ADU in San Diego
Is a garage conversion or a detached ADU better in San Diego?
A garage conversion is the lower-cost path: 307 City of San Diego conversion permits in 2026 declared a median $89,600, versus $154,300 for 293 new detached ADUs, a gap of about $64,700. A detached ADU buys more privacy, layout freedom and usually rent, but adds a foundation, utility runs and, in most cases, required solar.
| Garage / room conversion | New detached ADU | |
|---|---|---|
| 2026 City permits | 307 | 293 |
| Median declared value | $89,600 | $154,300 |
| Middle half | $59,600–$144,400 | $102,900–$198,800 |
| Structure | Reuses slab, walls, roof (often needs moisture, insulation, fire separation) | All new: foundation, framing, roof |
| Utilities | Often extended from main house | Usually new runs; SDG&E service change common |
| Solar | Generally not required | Generally required on new detached units |
| Parking | Garage spaces are lost | Garage kept |
Choose a conversion if
- The garage is permitted, structurally sound and has adequate ceiling height.
- You want the fastest payback and can give up covered parking.
Choose detached if
- You want a premium, private unit with its own entry and outdoor space.
- You plan to hold long term and want maximum rent and resale appeal.
- You may build two: the first two ADUs on a lot are exempt from City Development Impact Fees.
Neighborhood figures: College Area · City Heights · Clairemont · North Park · Mira Mesa · Pacific Beach · South Park & Golden Hill · Encanto
Talk to vetted local pros
Questions San Diego homeowners ask
How much more does a detached ADU cost than a conversion?
About $64,700 more at the 2026 City permit medians ($154,300 vs $89,600), before design, fees and utility work.
Do ADUs pay impact fees in San Diego?
Development Impact Fees are waived for ADUs under 750 sq ft and for the first two ADUs on a property.
Which adds more value?
A detached unit usually rents and resells better because it is fully separate; a conversion pays back faster.
Get both options priced
Serious homeowners can compare a conversion and a detached design from up to 3 vetted builders. Free.