Contra Costa County, CA Noise Ordinances: Construction Hours (2026)

Ask the county and the answer is direct. The Department of Conservation and Development's Code Enforcement FAQ reads: "In general, there are no restrictions for construction working hours within Contra Costa County. Occasionally, as a conditional of approval, the Planning Division may restrict days and times of construction to a permit approval." A contractor framing an addition at 6:30 a.m. on a Sunday under an ordinary building permit is not breaking a county rule, because there is no rule to break. DCD's June 14, 2024 memo to the Municipal Advisory Councils names this as one of the county's acknowledged gaps: limits on construction noise and hours apply "only for larger projects that can be conditioned as part of the approval process," and "construction projects that only require a building permit are not subject to the same limitations."

Where conditions of approval exist, they bite. The Board of Supervisors' March 5, 2024 staff report (File 24-0696) describes the standard: "The standard construction window imposed is 8:00 A.M. to 5:00 P.M., Monday through Friday, and prohibited on State and Federal holidays." Those conditions attach to discretionary approvals, subdivisions, land use permits, development plans, not to over-the-counter building permits. To find out whether a specific site carries them, the FAQ points to one office: "The Planning Division 925-655-2705 retains the information about specific sites."

Grading is the one trade with hours in the code itself. Under § 716-8.1004 of the Grading Ordinance, "if operations under the permit are within five hundred feet of residential or commercial occupancies, except as otherwise provided by conditions of approval for the project, grading operations shall be limited to weekdays and to the hours, between seven-thirty a.m. and five-thirty p.m., except that maintenance and service work on equipment may be performed at any time." Section 716-8.1008 adds that grading "operations shall be controlled to prevent nuisances to public and private ownerships because of dust, drainage, removal of natural support of land and structures, encroachment, noise, and/or vibration." Both apply only to work done under a county grading permit.

Enforcement follows the paperwork. DCD's Code Enforcement Program (30 Muir Road, Martinez; 925-655-2710) enforces "the building and zoning ordinances for the unincorporated areas", including work performed without permits, and it is not a noise agency; it does not police construction hours where none have been imposed. A project working outside hours written into its own approval is violating a condition of its entitlement, and the Planning Division that holds those conditions is the place to report it. Construction inside Concord, Richmond, Antioch or any other incorporated city falls under that city's code, not the county's.