La Mesa, CA Building Safety: Fire Sprinkler Requirements (2026)

La Mesa ties ADU fire-sprinkler duties directly to whatever applies to the primary residence on the same lot. Section 24.05.020(D)(8)(a)(viii) states that accessory dwelling units are not required to provide fire sprinklers if sprinklers are not required for the primary residence, and it adds that building an ADU cannot be used to trigger a new sprinkler mandate for the existing primary dwelling. Junior accessory dwelling units get the same protection under Section 24.05.020(D)(9)(i), which exempts a JADU from fire sprinklers or fire-attenuation specifications whenever the primary residence does not need them, while still allowing the city to assess an inspection confirming the JADU meets its development standards.

Both provisions read together with Section 24.05.020(D)(8)(a)(vii), which requires attached and detached ADUs to comply with all local building and fire code requirements as appropriate, meaning the exemption is narrow: it removes only the sprinkler trigger tied to adding a second unit, not the underlying California Building and Fire Code review the Community Development Department and Heartland Fire and Rescue still conduct on the ADU permit itself, including exterior access and fire-safety setback findings made by the fire marshal or building official for ministerial conversions.