La Mesa, CA Noise from Specific Sources: HVAC & Mechanical Noise (2026)

Section 10.80.090 targets fixed mechanical noise sources: it is unlawful to install or operate any machinery, equipment, pump, fan or air conditioning apparatus that creates noise exceeding the Section 10.80.040 ambient base noise level by more than five decibels, measured at the property line of any affected property. Subsection (a) requires the installer of such equipment to furnish the city's Department of Building Inspection and Housing a certificate showing the unit, as proposed, can operate within that five-decibel allowance without added baffling or construction changes.

Subsection (b) then makes installing the equipment without a permit, or without furnishing that certificate, prima facie evidence of a violation, and it bars operating the device at all until the permit is obtained and the certificate furnished. Because the allowance floats off the Section 10.80.040 table, the actual decibel ceiling for an HVAC unit or pool pump varies by zone and time: a unit next to an R1 or R2 home faces a 55-decibel ceiling overnight, 50 decibel ambient plus 5, but a 65-decibel ceiling during the day.

The rule reaches residential air conditioners, pool equipment pumps and rooftop commercial units alike, and complaints are investigated by the La Mesa Police Department together with the city's building inspection staff, who can verify whether the required compliance certificate was filed. A violation is an infraction under the general penalty clause, Section 1.01.080, and, as with other Chapter 10.80 provisions, the city may seek an injunction against a chronic noise source under Section 10.80.060.