King County, WA Noise from Specific Sources: HVAC & Mechanical Noise (2026)
Key Facts
- Daytime residential limit
- 55 dB(A) residential-to-residential
- Nighttime reduction
- -10 dB(A), 10pm-7am weekdays
- First offense fine
- up to $125 civil infraction
- Scope
- unincorporated King County only
- Enforcing agency
- King County Sheriff's Office
Summary
In unincorporated King County, air conditioners, heat pumps and other stationary equipment noise must stay under the county's district-based sound level table, dropping 10 dB(A) overnight.
It is unlawful for any person to cause sound, or for any person in possession of property to permit sound originating from such property, to intrude into the real property of another person whenever such sound exceeds the maximum permissible sound levels established by this chapter.
Full Breakdown
King County Code section 12.86.100 makes it unlawful for sound from any source, including an HVAC unit, to intrude onto a neighbor's property above the maximum permissible levels set in section 12.86.110's table, which runs 49-70 dB(A) depending on both properties' zoning district (55 dB(A) residential-to-residential in daytime). Section 12.86.120.A cuts every limit by 10 dB(A) between 10 p.m.-7 a.m. weekdays (10 p.m.-9 a.m. weekends) in rural or residential districts, pulling a residential AC or heat pump down to 45 dB(A) at night. No HVAC exemption exists; the chapter's stationary-equipment exemption covers only existing utility water-conveyance gear and electrical substations. This applies only in unincorporated King County - Seattle, Bellevue, Kent, Renton, Federal Way, Auburn and the county's other 20-plus cities enforce their own separate noise codes.
Violations & Fines
First violation in 12 months: civil infraction up to $125; second up to $250; each later violation doubles; a third can trigger prosecutor referral for an injunction (K.C.C. 12.86.700).
Frequently Asked Questions
Does this cover a noisy AC unit in Seattle?
What's the nighttime limit for a heat pump heard on a neighboring residential lot?
Is there an HVAC-specific exemption?
Sources & Official References
Other rules in King County
Compare King County to another location·View the Washington noise from specific sources overview
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