La Mesa ADU Rules & Pre-Approved Plans (PADU)

The key standards, from the city's own ADU page

Summarized from the City of La Mesa's official ADU page (Accessory Dwelling Units) — nothing here comes from aggregators or other cities' rules. Rules change; confirm the current standards with the city before relying on them.

What counts	ADUs and JADUs are additional living units on the same property as a single-family home. An ADU is self-contained — kitchen, bathroom, sleeping, and living space — and can be attached to the main home or detached. A JADU is smaller, is contained within the existing footprint of the primary residence, has a private entrance, and is often converted from a garage, basement, or attic.
The standards	The City publishes an ADU/JADU Development Matrix summarizing its development standards, linked from its ADU page. The City states that it complies with all state housing and land use bills as soon as they take effect — so La Mesa's standards track current California ADU law.
Pre-approved plans (PADU)	The City of La Mesa has developed pre-approved ADU plans to encourage construction. Per the City's ADU page and program materials, the five plans are: Plan A — 224 sq ft studio; Plan B — 400 sq ft, 1 bed; Plan C — 499 sq ft, 1 bed; Plan D — 990 sq ft, 2 bed; Plan E — 1,199 sq ft, 3 bed.

Also on the city's page

Using a PADU plan, step by step (from the City's page): (1) select a pre-approved plan and email [email protected] to request the official construction permitting plan set; (2) develop a site plan and supplemental documents — energy calculations for all projects, and a soils report only if the ADU is over 500 sq ft; (3) fill in the project-specific information on the plan set; (4) submit the application through the City's MaintStar Permitting Portal.
Planning Division: City Hall, 8130 Allison Avenue, La Mesa, CA 91942 · 619-463-6611.
Because La Mesa ties its standards to state law as it changes, confirm the current matrix on the City's page before designing around any specific number.

Source: the City of La Mesa's official ADU page (Accessory Dwelling Units) — https://www.cityoflamesa.gov/1821/Accessory-Dwelling-Units (read November 2026). The five PADU plan sizes are as published in the City's ADU page and program materials. This summary is general information about the city's published rules. It is not legal advice and not a determination about any property — whether a specific lot can host an ADU is a question for the city and a licensed builder's feasibility review.

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