How Much Does an ADU Cost in San Diego?
There is no single San Diego ADU price. Your unit type, your lot and the agency that issues your permit all move the number. Here is what drives it and how owners pay for it.
- We explain every option, not just one product
- Matched with lenders who finance ADUs
- No obligation to take any offer
How a San Diego ADU budget comes together
Start with the type of unit. A garage conversion reuses a slab, walls and a roof. A detached unit starts from bare ground, so it carries more site work and construction.
Then add the parts owners forget: plans, permit fees, soil work and utility lines. Fees depend on who issues your permit: the City of San Diego, the County of San Diego for unincorporated areas, or your own city, such as Chula Vista.
At a glance
- Biggest swing: detached build versus conversion
- Easy to miss: utility upgrades and site work
- Who sets fees: your city or county
What drives San Diego ADU cost
Two units of the same size can land far apart. A flat lot with the sewer close by costs less than a sloped lot that needs grading or a long utility run. California law limits impact fees on smaller ADUs, so size can affect fees too. Confirm current fees with your city or county.
| Cost line | What moves it |
|---|---|
| Design and plans | Custom design or a ready made plan, plus engineering |
| Permits and fees | The issuing agency and unit size |
| Site work and foundation | Slope, soil and equipment access |
| Utility connections | Distance to sewer and water, and panel upgrades |
| Construction | Unit type, size and number of bathrooms |
| Finishes | Flooring, cabinets, fixtures and appliances |
Typical price range
A written estimate from a builder who has walked your lot is the most reliable number you can get. Ask for it broken down by the lines above so you can match it to a loan.
Once you have a number
If your equity covers the estimate, a HELOC lets you draw as invoices arrive. If not, a construction loan can lend against the finished value. Either way, check the permit fees at your address.
San Diego HELOC for an ADU
Draw on your equity as builder invoices arrive.
San Diego ADU construction loans
Paid to your builder in draws, lending on the finished value.
San Diego ADU permits and fees
Who issues your permit and how to budget for fees.
San Diego ADU cost questions
How much does an ADU cost in San Diego?
It depends on unit type, size, your lot and the permit fees at your address. A garage conversion usually costs less than a detached unit. Trust a line by line builder estimate.
What is the cheapest way to build an ADU in California?
Converting space you already have, such as a garage, is usually the lowest cost route because the slab, walls and roof are already there.
What's one drawback of an ADU?
The upfront cost. Most owners borrow against the home to pay for it, so plan the full budget before you commit.
Talk to a lender who finances ADUs
Tell us your project type, rough budget and timeline and we will connect you with a lender who finances ADUs.
Talk to a specialist: (555) 555-0143
Thanks. We have your details and a lender who finances ADUs will be in touch, usually within one business day.