How Much Does an ADU Cost in San Diego, CA?
ADU costs in San Diego depend on the type of unit, size, site conditions, and finishes. Below are typical all-in ranges — including construction, design, and permits — based on recent CA market conditions.
Typical cost ranges in San Diego
| Project type | Estimated range |
|---|---|
| Detached ADU (new build) | $180,000–$400,000 |
| Garage conversion | $100,000–$185,000 |
| Design & permitting | $15,000–$40,000 (varies) |
| Utility connections | $5,000–$30,000 (varies) |
These are editorial estimates, not quotes. Actual costs vary significantly by property, scope, and contractor — request multiple quotes before budgeting.
What drives ADU cost in San Diego
- Size: larger units cost more in total but often less per square foot.
- Site conditions: slopes, mature trees, drainage, and access for equipment.
- Utilities: distance to sewer/water/electrical, panel upgrades, or new service.
- Foundation and structure: especially for garage conversions with older slabs.
- Finish level: kitchens and bathrooms are the most expensive rooms per square foot.
- Design and permits: custom design costs more than pre-approved plans where San Diego offers them.
FAQ
How much does an ADU cost in San Diego?
Most detached ADUs in San Diego land in the $180,000–$400,000 range all-in, depending on size, finishes, and site conditions. Garage conversions typically run $100,000–$185,000. These are editorial estimates — get multiple quotes for your specific property.
Do I need a permit to build an ADU in San Diego?
Yes. Every ADU and garage conversion in San Diego requires building permits. The good news: California law requires ministerial (no public hearing) approval for code-compliant ADUs. State law's 60-day review applies; San Diego's standard plans and dedicated ADU review can be faster. Typical custom projects run 2–4 months from design start to permit issuance.
How long does it take to build an ADU in San Diego?
Plan for 3–6 months of design and permitting, then 4–8 months of construction for a detached ADU. Garage conversions are usually faster — often 3–5 months of construction once permits are issued.
Can I rent out my ADU in San Diego?
Yes — long-term rentals (30+ days) of ADUs are allowed statewide in California. Short-term rental rules vary by city, so check San Diego's short-term rental ordinance before planning Airbnb-style use.
Ready to compare local pros? See ADU builders in San Diego or garage conversion contractors in San Diego.