La Mesa’s Five Preapproved ADU Designs Meet a New 2026 Building Code: What Applicants Should Check

LA MESA, San Diego County — October 23, 2026. Homeowners who want to build an accessory dwelling unit have access to five preapproved ADU designs from the City of La Mesa. Those plans can simplify the early design process, but the city’s official ADU resource page lists further steps that remain the property owner’s responsibility. An existing rendering is not, on its own, a building permit.

Choosing the plan is only Step 1

La Mesa instructs applicants to select a preapproved plan and contact its Planning Department at Planning@cityoflamesa.gov to obtain the official construction-permitting set. Applicants must then develop a site plan and other supplemental documents; energy calculations are needed for all projects, while the city’s posted process says a soils report is needed for units larger than 500 square feet. More detailed requirements may apply depending on lot conditions and the specific design.

The 2026 code transition matters

The La Mesa Building Division says new applications received after its December 18, 2025 deadline would be processed under the 2025 California Building Code cycle effective in 2026, with offices reopening January 5. Homeowners using designs or estimates saved from earlier years should verify that all structural, energy, safety and electrical details comply with current requirements. An old quotation may be incomplete under the new rules.

What could a preapproved plan save?

Reusing a city’s previously reviewed design can reduce repeated architectural and plan-review work. It does not eliminate site-specific approval, utility connection work, grading, foundation engineering, permit and inspection fees. If an owner is comparing different builders, every bid should specify whether the contractor handles drawings, drainage, fire and electrical requirements, agency coordination and final city inspections.

Where to get a real estimate

The city lists its Building Division at 8130 Allison Avenue, phone 619-667-1176, and email building@cityoflamesa.gov. Use the latest application instructions from the ADU program, then request a parcel-specific checklist and fee estimate before paying for plans or construction. Residents can also check the Community Development Department for permit and zoning information.

Read La Mesa News and El Cajon News. Send source-backed updates and corrections to the newsroom. Support this independent local newspaper.

Sources: City of La Mesa Accessory Dwelling Units and Building Division pages; the city’s current preapproved-plan and submittal instructions. Informational reporting, not a construction approval.

YOUR LOCAL NEWSPAPER NEEDS YOU

Help this community newspaper grow

Your support helps build coverage for the people and places this local newspaper serves.

Donate once by card ↗

Help La Mesa News grow Help strengthen reporting on La Mesa: community voices, important decisions and local life.

Support La Mesa News

Choose how to support La Mesa News:

Credit / Debit Card via Stripe

Choose an amount from $1. One-time support through the publisher's LINKERNO Stripe account.

Continue with PayPal Continue with Zelle

Zelle payments go to Vitaly Ataev Troshin. Please verify the recipient in your bank before sending. Availability depends on your bank.

Optional reader support. When possible, add “La Mesa News” to the payment note. Contributions are not advertised as tax-deductible. Support does not influence editorial decisions.

Optional support through the publisher. Contributions are not advertised as tax-deductible and never buy editorial influence.

La Mesa News — Your Community Newspaper

Have a correction, news tip, local announcement, or story to submit? Contact our editorial team. All submissions are reviewed before publication.