San Marcos, CA Accessory Structures: ADU Owner Occupancy (2026)
Key Facts
- Owner-occupancy rule
- Main house or Junior ADU must be owner-occupied
- Recorded where
- Deed restriction with County Recorder
- Required before
- Building permit issuance for the Junior ADU
- Applies to
- Junior ADUs only, not standard ADUs
- Governing section
- Municipal Code § 20.410.060.O.5
Summary
San Marcos requires an owner-occupancy deed restriction before any Junior ADU gets a building permit. Municipal Code § 20.410.060.O.5 mandates that either the primary home or the Junior ADU be owner-occupied, recorded against the property with the County Recorder.
O. Deed Restriction. Prior to the issuance of a building permit for a Junior ADU, a Deed (Land Use) Restriction shall be recorded with the County Recorder that includes all the following:1.Prohibiting of the sale of the Junior ADU separately from the sale of the single-family residence, including a statement that the deed restriction may be enforced against future purchasers; ... 5.Requiring that one (1) of the dwelling units (main or Junior ADU) shall be owner occupied.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 14 Update 1).
Full Breakdown
5 is the owner-occupancy piece of that restriction: it requires that one of the two dwelling units, either the main house or the Junior ADU, be owner occupied. 4: a prohibition on selling the Junior ADU separately from the single-family residence (with a statement that the restriction is enforceable against future purchasers), a cap confirming the Junior ADU's maximum gross floor area at 500 square feet, a requirement that the Junior ADU's independent exterior access be retained, and a requirement that it be rented for terms of 30 days or longer if rented at all.
H addresses standard ADUs separately and does not carry the same deed-restriction package. C reinforces the point earlier in the chapter, describing the Junior ADU rule as requiring that 'either the primary dwelling or the Junior ADU must be owner occupied' as a baseline condition of the unit type itself, before construction standards are even reached.
Violations & Fines
Building or occupying a Junior ADU without recording the required deed restriction, including the owner-occupancy commitment under O.5, means the City cannot lawfully have issued the building permit for that unit. An existing Junior ADU found out of compliance, for example where neither unit is owner-occupied, is subject to code enforcement and can jeopardize the property's ability to rent both units at all.
Frequently Asked Questions
Do I have to live on the property if I build a Junior ADU?
Does the owner-occupancy rule apply to a regular detached ADU too?
What else has to be in the Junior ADU deed restriction?
Sources & Official References
Other rules in San Marcos
California rules heatmap·Compare San Marcos to another location·View the California accessory structures overview
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ADU Owner Occupancy in Nearby Cities
How other cities in San Diego County handle adu owner occupancy.