Williamson County, TN Noise from Specific Sources: HVAC & Mechanical Noise (2026)
Key Facts
- Daytime residential limit
- 60 dBA, 7 a.m.-10 p.m.
- Nighttime limit (non-rural)
- 55 dBA after 10 p.m.
- Nighttime limit (rural, 5+ acres)
- 50 dBA after 10 p.m.
- Commercial/institutional limit
- 65 dBA, day and night
- Measurement method
- A-weighted, slow-response 10-min Leq
- Applies only to
- Unincorporated Williamson County
Summary
Continuous mechanical noise, such as rooftop condensers, compressors and chillers on covered commercial, industrial or institutional uses, is capped by Williamson County's Zoning Ordinance at 60 dBA by day and 55 or 50 dBA at night when it reaches a neighboring house. The county does not name HVAC units specifically; they fall under the ordinance's generic "Non-Sound Production Devices" category.
(B) GENERAL STANDARDS (1) Sounds produced by, generated on or associated with the uses outlined in Section 16.02(A) above, other than sounds produced by Sound Production Devices, shall not exceed the A-weighted 10-minute Leq (slow response) limits listed in Table 16:02-1: Maximum Noise Standards-Non-Sound Production when measured outdoors anywhere within the Receiving Property boundaries.
Full Breakdown
Article 16, Section 16.02(B)(1) of the Williamson County Zoning Ordinance, effective January 1, 2013, sets the county's outdoor mechanical-noise ceiling for the 13 use categories listed in Section 16.02(A), including the Industrial Use Classification, Agricultural Support and Services, Commercial uses, Public and Institutional uses, and other listed non-residential activities. The Ordinance does not single out HVAC units by name; instead it groups all continuously running mechanical noise, such as rooftop condensers, compressors, chillers and exhaust fans, into the catch-all Non-Sound Production Devices category measured against Table 16.02-1, using an A-weighted, slow-response 10-minute Leq.
Where that equipment sits on a covered use and its noise reaches a nearby house, the limit is 60 dBA from 7 a.m. to 10 p.m., falling to 55 dBA overnight on residential parcels under five acres or 50 dBA overnight on rural parcels of five acres or more; commercial and public/institutional receiving properties get a flat 65 dBA around the clock, and agricultural receiving land is capped at 60 dBA by day and 50 dBA at night. Applicants for a Site Plan or Special Use permit covering one of the listed uses must, under Section 16.02(G), describe in writing how mechanical equipment noise will be mitigated, and Section 16.02(D) lists acceptable measures such as an earthen berm, enclosure, or siting equipment to use natural topography as a barrier toward the nearest home.
Violations & Fines
Running mechanical equipment above Table 16.02-1's dBA ceiling is a misdemeanor under Section 22.07(A): fines run $10 to $50 per offense under Tenn. Code Ann. §13-7-111, and Section 22.03(F) makes each day of continued exceedance a separate offense. The Codes Compliance Director investigates complaints filed with the Community Development Department under Section 22.05(B)-(C) and may pursue civil enforcement under 22.05(D) in addition to the criminal fine.
Frequently Asked Questions
Does the county noise ordinance regulate my home air conditioner?
How loud can a commercial building's rooftop equipment be at a nearby house?
What must a developer show about mechanical noise before getting a Site Plan approved?
What's the penalty for equipment that keeps exceeding the noise table?
Sources & Official References
Other rules in Williamson County
Compare Williamson County to another location·View the Tennessee noise from specific sources overview
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