Thornton, CO Noise Ordinances: Decibel Limits (2026)
Key Facts
- Residential limit
- 55 dB(A) day, 50 dB(A) night
- Nonresidential (non-industrial) limit
- 60 dB(A) day, 55 dB(A) night
- Industrial limit
- 80 dB(A) day, 75 dB(A) night
- Day/night split
- 7:00 a.m. to 7:00 p.m. is day
- Measurement point
- Property line, 4+ feet above grade
- Governing section
- City Code § 38-441(c)(1)-(2), Table A
Summary
Thornton caps continuous sound at 55 dB(A) by day and 50 dB(A) by night in residential districts, 60/55 dB(A) in other nonresidential districts, and 80/75 dB(A) in industrial districts, measured at the property line under Table A of § 38-441(c).
(2)The maximum permissible sound pressure levels of any continuous source of sound is given in subsection (c), Table A, Sound Pressure Level Limits. Sound pressure levels in excess of the limits for the district in which the source is located are considered an unreasonable noise and are prohibited. Table A. Sound Pressure Level Limits District dB(A) During the Day, 7:00 a.m. to 7:00 p.m. dB(A) During the Night, 7:00 p.m. to 7:00 a.m. All Residential Districts 55 50 Nonresidential Districts Except Industrial 60 55 Industrial Districts 80 75
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 65).
Full Breakdown
; Nonresidential Districts Except Industrial, 60 dB(A) day and 55 dB(A) night; and Industrial Districts, 80 dB(A) day and 75 dB(A) night. Sound exceeding the limit for the district where the source sits is deemed an unreasonable noise and prohibited outright. Subsection (c)(1) specifies how the reading is taken: at the approximate property line, or at least 25 feet from a motor vehicle, at a height of at least four feet above grade, using an A-weighted sound level meter of standard design. Table A is the baseline standard that subsection (c)(3) applies to vehicle repair, testing, machinery, pumps, and air-conditioning equipment, and it is cross-referenced throughout the noise article, including construction activity, power equipment, loading operations, and public address systems, wherever those sections do not set their own separate numeric limit under subsection (c)(4).
Violations & Fines
Exceeding Table A's limit for the applicable district is itself declared "unreasonable noise" and prohibited under § 38-441(c)(2), triggering the same enforcement path as other noise violations: an immediate summons and complaint, or a written notice to abate giving 24 hours to 5 days to fix the problem, under § 38-452(d). The city may hire an outside acoustical expert for disputed readings and bill the cost to the violator if a violation is confirmed, under § 38-452(c).
Frequently Asked Questions
What is the maximum noise level allowed in a Thornton residential neighborhood?
How does Thornton measure decibel violations?
Are Thornton's decibel limits the same day and night?
Sources & Official References
Other rules in Thornton
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