City of San Marcos pre-approved ADU plans
The pre-approved ADU plans City of San Marcos publishes, copied as published, with a link to the official page and the date A-du last checked it.
Official page: https://www.sanmarcosca.gov/Business-Services/Building-Division/Permit-Ready-ADUs (A-du last checked it October 12, 2026).
A-du is not affiliated with HCD or any city or county. This page copies what each agency publishes about its pre-approved ADU plans and links to the official page. Check the agency's page before you rely on anything here. Nothing on this page is legal advice.
The plans
498 Square
- Designer:
- Not named on the agency page
- Status:
- No status label on the agency page
A-du could not load the agency page to re-check this plan on October 12, 2026. Check the official page.
748 Rectangle Long
- Designer:
- Not named on the agency page
- Status:
- No status label on the agency page
A-du could not load the agency page to re-check this plan on October 12, 2026. Check the official page.
749 Square
- Designer:
- Not named on the agency page
- Status:
- No status label on the agency page
A-du could not load the agency page to re-check this plan on October 12, 2026. Check the official page.
863 L-Shape
- Designer:
- Not named on the agency page
- Status:
- No status label on the agency page
A-du could not load the agency page to re-check this plan on October 12, 2026. Check the official page.
992 Rectangle
- Designer:
- Not named on the agency page
- Status:
- No status label on the agency page
A-du could not load the agency page to re-check this plan on October 12, 2026. Check the official page.
999 L-Shape
- Designer:
- Not named on the agency page
- Status:
- No status label on the agency page
A-du could not load the agency page to re-check this plan on October 12, 2026. Check the official page.
Getting a plan permitted
A pre-approved plan still needs a building permit for your lot. For free plans published by a California city or county, A-du offers an optional flat-fee permitting service. It is performed by Chris Koss, AIA (California license C-39677), who owns A-du, so A-du has a financial interest in it. You can always take a free plan straight to your building department instead. Open any plan on A-du Build to see what applies to it.
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