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San Mateo County, CA Noise Ordinances: Construction Hours (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Construction hours in San Mateo County, CA, sometimes called construction noise rules or contractor work-hour ordinances, set when contractors can run power tools, hammers, and heavy equipment.

Key Facts

Weekday cutoff
6:00 p.m.-7:00 a.m. barred
Saturday cutoff
5:00 p.m.-9:00 a.m. barred
Sundays/holidays
barred all day
Applies to
unincorporated area only

Summary

In unincorporated San Mateo County, construction noise is only exempt from the noise code between set weekday, Saturday, and blackout-day hours.

City-specific rules exist: Daly City, and Redwood City have their own construction hours rules that differ from San Mateo County's county-level regulations. If you live in one of those cities, check the city-specific page instead.

Noise sources associated with demolition, construction, repair, remodeling, or grading of any real property, provided said activities do not take place between the hours of 6:00 P.M. and 7:00 A.M. weekdays, 5:00 P.M. and 9:00 A.M. on Saturdays or at any time on Sundays, Thanksgiving and Christmas.f)All mechanical devices, apparatus or equipment which are utilized for the protection or salvage of agricultural crops during periods of potential or actual frost damage or other adverse weather conditions.g)Mobile noise sources associated with agricultural operations provided such operations do not take place between the hours of 8:00 P.M. and 7:00 A.M.h)Mobile noise sources associated with agricultural pest control through pesticide application provided that the application is made in accordance with restricted material permits issued by or regulations enforced by the Agricultural Commissioner.i)Noise sources associated with the maintenance of real property used for residential purposes provided said activities take place between the hours of 7:00 A.M. and 8:00 P.M.j)Any activity to the extent regulation thereof has been preempted by State or Federal law. (Prior code § 4956; Ord. 2803, 10/19/82; Ord. 3208, 03/06/90)

Source: San Mateo County Code § 4.88.360 (Noise Control — exemptions)View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 47).

Full Breakdown

County Code § 4.88.360(e) exempts demolition, construction, repair, remodeling and grading noise from the chapter's dBA limits only if it does not occur between 6:00 p.m. and 7:00 a.m. on weekdays, 5:00 p.m. and 9:00 a.m. on Saturdays, or at any time on Sundays, Thanksgiving, or Christmas. Work outside those windows must instead meet the regular Table I exterior noise standards.

Violations & Fines

Health Officer/Sheriff enforcement; violating the noise chapter is a misdemeanor, each day a separate offense (§ 4.88.460).

Frequently Asked Questions

Can contractors work Sunday in unincorporated San Mateo County?
The construction noise exemption never applies on Sundays, Thanksgiving, or Christmas, so work must meet normal Table I noise limits those days.
Does this cover Redwood City construction sites?
No, this is County Code Chapter 4.88, which governs only the unincorporated area, not the incorporated cities.

Sources & Official References

Other rules in San Mateo County

All San Mateo County rules

How San Mateo County compares: Cities with the Strictest Construction Hours·California rules heatmap·Compare San Mateo County to another location·View the California noise ordinances overview

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Construction Hours in Cities Across San Mateo County