Detached Garage Conversion Cost across San Diego County
Detached garage conversions in San Diego County tend to land toward the middle and higher end of the overall $40,000-$150,000 range because new utility trenching from the main house to the standalone structure adds cost that an attached garage does not require.
What moves the price
- Trenching distance for new electrical, water, and sewer lines
- Whether the detached structure needs a separate electrical meter
- Foundation and structural condition of the existing detached garage
- Conversion type chosen (bedroom vs. full ADU; a detached garage cannot be a JADU)
What's included
- Underground utility trenching to the detached structure
- Electrical service extension or new meter where applicable
- Plumbing supply and drain line extension
- Insulation, flooring, and exterior wall infill
Common questions
Why does trenching cost so much on a detached garage?
Running new electrical, water, and sewer lines underground from the main house to a standalone structure means trenching through the yard, which is labor-intensive and sometimes requires landscape or hardscape repair afterward.
Do detached garage ADUs need their own electrical meter?
Not required by California ADU law, but some homeowners add one to simplify utility billing if the unit will be rented long-term. It adds cost and requires coordination with the local utility.
Is a detached garage better for rental privacy?
Yes, a detached full ADU with its own entry and utilities offers the most separation from the main home, which is a common reason homeowners choose detached conversions specifically for rental income.
Need a written detached cost for your project?
Insured local crews across San Diego County put the scope in writing.