How much does an ADU cost in San Diego?
The median single-ADU building permit in the City of San Diego declared $120,900 of construction in 2026 (middle half $76,000–$197,700, 750 permits). Garage and other conversions ran a median $89,600 and new detached ADUs $154,300. Declared value excludes design, City fees and utility work.
Source: City of San Diego permits, 750 single-ADU permits issued Jan 1–Oct 15, 2026 · Last updated: October 17, 2026 · Prices are public ranges or declared permit values, not quotes.
2026 ADU costs from City of San Diego permits
| ADU type (City of SD, 2026) | Permits | Low (25%) | Median | High (75%) |
|---|---|---|---|---|
| Any single-ADU permit | 750 | $76,000 | $120,900 | $197,700 |
| Conversion (garage, room, accessory building) | 307 | $59,600 | $89,600 | $144,400 |
| New detached ADU | 293 | $102,900 | $154,300 | $198,800 |
| Permits adding 2+ ADUs | 333 | $151,300 | $247,200 | $330,300 |
Source: City of San Diego permit data (building permits issued Jan 1–Oct 15, 2026 that add at least one ADU). Valuation is the construction value the applicant declared to the City, not a final invoice or a quote. “Conversion” and “detached” are sorted by words in the permit description; some permits also include work on the main house.
What moves the price
- Conversion vs. new build: converting a garage reuses the foundation and shell, which is why its median is about $64,700 below a new detached unit.
- Size and stories: two-story and over-garage units need more structure and often more engineering.
- Utilities: a new sewer lateral, water meter or electrical panel upgrade can each add thousands. See what comes next.
- Fire zone and site: many permits note a Very High Fire Hazard Severity Zone (VHFSZ), which brings wildfire-resistant construction rules. Slopes and retaining walls add cost.
- Fees: see the fee section of the price guide.
How it works
- Fill in the short form and check the consent box.
- A person reads it. We may share it with up to 3 licensed local ADU builders.
- They contact you with questions or a quote. You decide.
Free guides
- ADU price guide with fees (sourced)
- How long ADU permits take in San Diego
- After your ADU: panel, solar, fence and landscaping timing
- Questions to ask an ADU builder
- Fair quote checklist and red flags
- Licensed firms with 2026 ADU permits
- San Diego price & contractor data hub
Last updated October 16, 2026.
How much does an ADU cost in San Diego?
In 2026 City of San Diego building permits for a single ADU, the median declared construction value was $120,900 (middle half $76,000–$197,700, 750 permits). Garage and other conversions ran lower (median $89,600); new detached ADUs ran higher (median $154,300). Declared value excludes design, City fees, utility work and often finishes, so real budgets run higher.
How long does an ADU permit take in San Diego?
For 2026 ADU building permits on the standard track, the median was 293 days from application to issue; a quarter took 170 days or less and a quarter took 486 days or more. Most of that time is usually correction rounds between the City and your designer.
Are ADUs exempt from impact fees in San Diego?
The City says ADUs under 750 sq ft, and the first two ADUs on a property, are exempt from Development Impact Fees (SDMC §142.0640). School fees, the General Plan Maintenance Fee, plan check and permit fees, and possibly water/sewer capacity fees still apply.
What usually comes after an ADU permit?
On the same parcels in 2026 City permits, the median gap to a sewer or utility permit was about 38 days, an electrical panel upgrade about 68 days, a fence about 112 days, and solar about 115 days.
Are you an ADU builder?
No. This is a free guide and quote-matching service. With your consent we pass your request to up to 3 local licensed builders. You never have to hire anyone.