About
About this guide
Last reviewed October 1, 2026
This is an independent information guide to accessory dwelling unit rules, permits, costs, and financing in San Diego County. It is not a contractor. It sells no design or construction services.
What this site is
The pages explain how detached ADUs, garage conversions, attached ADUs, and junior ADUs are commonly planned, permitted, and paid for. They are written for homeowners who want the official rules in plain language before they talk with a designer, a lender, or a contractor they choose themselves.
Where the facts come from
Rules and fees are taken from city, county, and state pages and are linked next to the summary. Primary sources used across the guides include:
Each guide shows a last-reviewed date. That date is when the page was checked against the sources linked on it. Ordinances and fee schedules change. Read the linked official page before you rely on a number.
What this site is not
Nothing here is legal advice, financial advice, or a substitute for a permit review by the agency that has jurisdiction over the lot. The cost calculator on the home page is a planning range. It does not ask for contact details and it is not a price from a builder.
The name in the logo is the name of this information site. It does not mean the publisher designs, permits, or builds ADUs.