Issaquah, WA Noise Ordinances: Decibel Limits (2026)

Chapter 18.518 of the Land Use Code applies to all land uses, and its noise section, LUC 18.518.020, works by adoption rather than by listing numbers. Subsection A adopts four sections of Chapter 173-60 WAC, as now existing or hereafter amended: WAC 173-60-020 on definitions, WAC 173-60-030 on identification of environments, WAC 173-60-040 on maximum permissible environmental noise levels, and WAC 173-60-050 on exemptions. Because the adoption covers the sections as hereafter amended, a state revision to those sections carries into Issaquah without a new City ordinance. The numeric zone and time-of-day table lives in the adopted WAC text, which the Issaquah code does not reproduce.

Subsection B turns the adopted limits into a mechanical equipment rule. No mechanical equipment can be operated so as to produce noise above the limits in subsection A, measured from the nearest property line of the parcel on which the equipment is located. The Community Planning and Development Department can require manufacturer's specifications before the building permit issues, and verification that the maximum level is not exceeded can be required after construction but before a certificate of occupancy.

Subsection C exempts noise caused by or resulting from an emergency situation as defined by the City's Comprehensive Emergency Management Plan. The same chapter is cross-referenced by the mineral resource standards in LUC 18.504.060(F), which say noise levels produced by an extractive operation may not exceed the levels specified by IMC 18.518.020.

Two numeric figures are printed for residential heat pumps and air conditioner condensers: LUC 18.508.030(D) sets 55 dbA during the day and 45 dbA at night at the property line, and LUC 18.518.020(D) exempts such units from the WAC-based limits when they do not exceed 73dbA or meet AHRI standard 270. Those rules are covered on the Issaquah HVAC equipment noise page.