8 county-level rules, plus city-specific rules for 4 cities in San Mateo County, California.
Verified from official government sources
Recreational fire pits in unincorporated San Mateo County follow California Fire Code section 307.4: recreational fires must stay at least 25 feet from structures and portable outdoor fireplaces at least 15 feet. Wood burning is also illegal anywhere in the Bay Area on any Spare the Air Alert day under BAAQMD Regulation 6, Rule 3.
All fireworks are illegal in unincorporated San Mateo County under County Ordinance Code Chapter 5.28, including state-approved 'Safe and Sane' fireworks like sparklers, fountains, and snakes. Possession, sale, and use carry a $1,000 fine, raised from prior levels in May 2021.
Properties in the Wildland-Urban Interface of unincorporated San Mateo County must maintain defensible space under California Public Resources Code 4291: 100 feet of clearance around structures. CAL FIRE / San Mateo County Fire conducts defensible space inspections, and roadside vegetation must be cleared to specified clearances.
Cal. Public Resources Code Sec. 4291 (Defensible Space Around Structures)
4291. (a) A person who owns, leases, controls, operates, or maintains a building or structure in the state responsibility area shall at all times do all of the following: (1) (A) Maintain defensible space of 100 feet from each side and from the front and rear of the structure, but not beyond the property line, except as provided in subparagraph (B). The amount of fuel modification necessary sha...
All backyard burning is prohibited throughout San Mateo County. Open burning is regulated by the Bay Area Air Quality Management District and requires a CAL FIRE burn permit, and may only occur on declared permissive burn days. Most residential yard-waste burning is illegal; use green-waste collection instead.
Unincorporated San Mateo County contains Moderate, High, and Very High Fire Hazard Severity Zones, with the Santa Cruz Mountains and coastal hills (La Honda, Pescadero, and similar) at the highest risk. Mapped zones trigger defensible space (PRC 4291), WUI building standards (CBC Chapter 7A), and real estate disclosure.
CAL FIRE Office of the State Fire Marshal - Fire Hazard Severity Zones
What are Fire Hazard Severity Zones? The State Fire Marshal is mandated to classify lands within State Responsibility Areas into Fire Hazard Severity Zones (FHSZ). Fire Hazard Severity Zones fall into one of the following classifications: Moderate High Very High The California laws that require Fire Hazard Severity Zones include California Public Resources Code 4201-4204, California Code of Reg...
Smoke alarms in unincorporated San Mateo County dwellings are governed by California Health & Safety Code section 13113.7 and the California Fire/Building Codes. Newer battery-only alarms must have a 10-year sealed non-replaceable battery, and alarms must be replaced 10 years after the manufacture date. Violations are a $200 infraction.
Small recreational backyard fires are allowed in unincorporated San Mateo County under California Fire Code section 307.4 with required setbacks and constant attendance, but all backyard burning of yard waste or trash is prohibited and wood fires are banned on Spare the Air days under BAAQMD Regulation 6, Rule 3.
Propane (LPG) storage in unincorporated San Mateo County follows the California Fire Code Chapter 61 and NFPA 58, enforced by CAL FIRE / San Mateo County Fire. Residential aggregate capacity is limited, tanks must meet setback and clearance rules, and permits are required above threshold quantities.
4 cities in San Mateo County have their own fire regulations rules. Each link goes to that city's dedicated page with code citations.
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