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San Diego County

La Mesa ADU Regulations

La Mesa publishes one of the most polished pre-approved plan libraries in the county — five PADU options ranging from a 224 sq ft studio to a 1,199 sq ft three-bedroom, plus a Guidebook with sample layouts on real La Mesa lots.

Official La Mesa ADU Page →Design Your ADU
Population
60,000
Permit Shot Clock
60 business days
Plus 15-day completeness review
Pre-Approved Plans
Yes — saves time & cost
ADU Programs
2 city programs listed
See program list below

What Makes La Mesa Different

  • Pre-Approved ADU (PADU) Plans A–E with published PDFs (224–1,199 sq ft)
  • City ADU Guidebook with sample layouts on real La Mesa lots
  • Soils report waiver under 500 sq ft saves real money
  • Ordinance 2023-2903 governs local ADU/JADU regulations

Size & Building Constraints

PADU catalog runs 224 sq ft (studio) to 1,199 sq ft (3BR). Local rules in Ordinance 2023-2903.

State guarantee: California requires every city to allow at least an 800 sq ft ADU exempt from local lot coverage, FAR, and front-setback rules.

Height baseline: 16 ft for detached, rising to 18 ft within ½ mile of major transit. Attached ADUs follow the primary home, capped at 25 ft.

Sketching an ADU for La Mesa? Draft a floorplan and walk through it in 3D — no sign-up required.
Open Design Tool →

Parking

Parking standards are governed by Ord. 2023-2903. Many lots qualify for transit-served exemption via the Trolley.

Permitting Process

Submit through the MaintStar Permitting Portal. Email Planning@cityoflamesa.gov for the official PADU construction sets.

State backstop: A complete ADU permit must receive a decision in 60 business days. If the city stalls past 30 business days, AB 253 lets you hire a certified private plan checker to force a 10-business-day decision.

Fees & Cost Programs

See the city ADU Guidebook and permit fees via the permitting portal. Soils report only required if the ADU is over 500 sq ft.

SB 543: No impact fees on ADUs ≤750 sq ft. Above 750 sq ft, fees scale to the ratio of ADU size vs the main home.

La Mesa ADU Programs

Preapproved ADU (PADU) Building Plans
La Mesa ADU Guidebook

Visit the official La Mesa ADU page (link in hero) for current eligibility and downloads.

Owner Occupancy & JADUs

Standard ADUs in La Mesa: no owner-occupancy required (made permanent in 2023).

JADUs: limited to 500 sq ft of interior livable space within an existing single-family home. Owner occupancy is required only when sanitation facilities are shared with the main house. JADUs cannot be used as short-term rentals (AB 1154 / SB 543).

Design an ADU that fits La Mesa’s rules

Sketch a floorplan, walk through it in 3D, and have our planners review it for size, height, and setback compliance before you submit to La Mesa.

Start Designing — FreeRequest Plan ReviewExplore FinancingCheck Local Rents

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Heads up: Local rules change frequently. This page summarizes publicly available state law (California Government Code §§ 66310–66342) and current local guidance for general planning purposes. Always confirm specifics with the La Mesa planning desk before submitting plans. ADUMetrics does not provide legal advice.