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 26, 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

Agency page for this plan See it on A-du Build

Listed on the agency page when A-du checked it on October 26, 2026.

748 Rectangle Long

Designer:: Not named on the agency page
Status:: No status label on the agency page

Agency page for this plan See it on A-du Build

Listed on the agency page when A-du checked it on October 26, 2026.

749 Square

Designer:: Not named on the agency page
Status:: No status label on the agency page

Agency page for this plan See it on A-du Build

Listed on the agency page when A-du checked it on October 26, 2026.

863 L-Shape

Designer:: Not named on the agency page
Status:: No status label on the agency page

Agency page for this plan See it on A-du Build

Listed on the agency page when A-du checked it on October 26, 2026.

992 Rectangle

Designer:: Not named on the agency page
Status:: No status label on the agency page

Agency page for this plan See it on A-du Build

Listed on the agency page when A-du checked it on October 26, 2026.

999 L-Shape

Designer:: Not named on the agency page
Status:: No status label on the agency page

Agency page for this plan See it on A-du Build

Listed on the agency page when A-du checked it on October 26, 2026.

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, you can request an optional flat-fee service, Permitting by Chris Koss, AIA. Chris Koss, AIA, a California-licensed architect who owns A-du, provides this permitting service personally under a separate written agreement with you (the Permitting Services Agreement). It is not performed by A-du, and A-du takes no part of his fee. 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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