San Mateo County, CA Ordinances (2026)

San Mateo County administers its own certified Local Coastal Program (LCP) and issues Coastal Development Permits (CDPs) for projects in the Coastal Zone, which covers roughly 240 sq…

Unincorporated San Mateo County bans dumping anything but rainwater into the county storm drain system under its Stormwater Pollution Prevention Ordinance.

Unincorporated San Mateo County requires the lowest floor of any new or substantially improved structure in an Area of Special Flood Hazard to sit at or above the regulatory…

Grading and construction sites in unincorporated San Mateo County must keep BMPs in place to stop erosion and sediment from reaching roads or storm drains.

Unincorporated San Mateo County bars grading, filling, new construction or any other development in a mapped Area of Special Flood Hazard, Floodway or Coastal High Hazard Area until…

Snow sidewalk clearing is not a regular concern in unincorporated San Mateo County's Mediterranean coastal climate, and the County has no dedicated snow-clearance ordinance. On the…

In unincorporated San Mateo County, the Planning and Building Code Compliance Section enforces property-maintenance standards and abates public nuisances such as accumulated refuse…

In unincorporated San Mateo County, the Planning Director can exempt interior remodels, repairs and minor exterior work from the discretionary site development permit, though a…

Unincorporated San Mateo County child care centers eligible for a ministerial permit must pass a fire safety inspection to Building Inspection Section standards before opening.

San Mateo County treats short-term rental violations as strikes: once a permitted unit racks up more than two documented violations in any 12-month period, the Department of Planning…

Anyone renting a home or room to guests for 30 days or less in unincorporated San Mateo County must register with the Tax Collector.

Under Zoning Regulations Section 6401.3(6)(a), the maximum number of short-term tenants is two persons per bedroom rented plus two additional persons. Children under 12 are not…

Section 6401.3(6)(b) requires each single-family STR to provide at least one on-site parking space (garage, driveway, or other on-site area), or at least two spaces if maximum…

Unincorporated San Mateo County bars almost every kind of cannabis business outright. County Code Section 5.148.050 lets the Planning and Building Department license only Mixed-Light…

Licensed cannabis cultivation sites in unincorporated San Mateo County must sit at least 600 feet from schools, day cares, youth centers and playgrounds.

Unincorporated San Mateo County allows adults 21+ to cultivate up to 6 cannabis plants per residence for personal, non-medical use under County Code Chapter 5.148 (Personal…

Unincorporated San Mateo County uses expedited solar permitting under California AB 2188 (Solar Rights Act). Residential rooftop systems under 10 kW qualify for same-day online permits…

California Civil Code §714 (Solar Rights Act) strongly limits HOA authority to restrict solar panels. HOAs in unincorporated San Mateo County (Emerald Hills, West Menlo Park…

Many San Mateo County cities (Redwood City, San Carlos, others) maintain 'Do Not Knock' registries that residents can join free of charge, and the County Sheriff requires all licensed…

Unincorporated San Mateo County requires commercial peddlers and solicitors to obtain a Peddler/Solicitor License from the San Mateo County Sheriff's Office, including a…

Unincorporated San Mateo County applies California's statewide just-cause eviction protections under AB 1482 (Civil Code §1946.2). After 12 months of tenancy, landlords must state an…

In unincorporated San Mateo County, a mobilehome park owner seeking a space-rent increase above the standard CPI cap must file a petition with the County Hearing Officer 60 days…

Unincorporated San Mateo County landlords must pay relocation benefits to tenants displaced when code enforcement declares their rental unit substandard or unsafe, under Chapter 3.108.

Unincorporated San Mateo County does NOT have a rental registration program. Landlords must comply with state habitability laws (Civil Code §1941.1) and the California Building Code…

Unincorporated San Mateo County has NO local rent control. State law AB 1482 (Tenant Protection Act, Civil Code §1946.2 and §1947.12) caps annual rent increases at 5% plus CPI (maximum…

To build a fence or hedge more than two feet above the standard height limit in unincorporated San Mateo County, owners outside the Coastal Zone must get a discretionary exception…

In the North Fair Oaks NMU commercial district, chain-link and corrugated metal fences are banned within 15 feet of the street, and visible street-facing fences top out at 4 feet.

San Mateo County's zoning code sets fence heights but does not allocate cost between neighbors. Boundary-fence cost sharing is governed by California Civil Code 841, which presumes…

In unincorporated San Mateo County, front-yard fences top out at 4 feet and side/rear fences at 6 feet, with a 4-foot cap near corner-lot intersections.

Under County Ordinance Code Chapter 7.60, it is unlawful and an infraction to abandon, park, store, or leave any abandoned, wrecked, dismantled, or inoperative vehicle on public or…

In unincorporated San Mateo County, the Director of Public Works assigns red, yellow, white, green and blue curb colors, each with a specific legal meaning drivers must follow.

Two Ordinance Code sections limit truck and trailer parking on unincorporated San Mateo County streets. Section 7.28.070 lets the Board of Supervisors designate parking zones that bar…

In unincorporated San Mateo County, parking in a designated loading zone beyond the time needed to load or unload passengers or freight is prohibited.

County-posted signs and curb markings set stopping, standing and parking limits on unincorporated San Mateo County streets.

For new construction in unincorporated San Mateo County, the County's local amendments to the California Building and Energy Codes require EV charging infrastructure. Adopted February…

Unincorporated San Mateo County has no blanket overnight on-street parking ban. The County Ordinance Code instead targets oversized vehicles and trailers on designated streets (Section…

Front-yard vehicle, boat and camper-shell parking is banned outside the driveway in the Broadmoor Police Protection District.

In unincorporated San Mateo County, exterior noise reaching a home, school, hospital, church or library cannot exceed the numeric limits in Table I of Code Section 4.88.330: as low as…

In unincorporated San Mateo County it's unlawful to make unreasonably loud, unnecessary, or unusual noise that disturbs a neighborhood's peace and quiet or annoys a person of normal…

Unincorporated San Mateo County has no dedicated gas-powered leaf blower ban or specific leaf-blower ordinance; the recent leaf-blower bans and electric-blower rebate programs are…

In unincorporated San Mateo County, letting a dog or cat habitually bark, meow, or disturb residents is banned as a public nuisance under County Ordinance Code § 6.04.060(c), enforced…

Operating sound amplifying equipment in a San Mateo County park or recreation area is unlawful without a Parks and Recreation Department permit under Section 3.68.130(b).

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

Section 7.80.010 lets San Mateo County's Director of Public Works, once the Board of Supervisors authorizes it, designate bicycle lanes on unincorporated county roads and post signs…

Anyone running a pawnbroker, secondhand dealer, junk dealer, or junk collector business in unincorporated San Mateo County must hold an annual License Board license under County Code…

Unincorporated San Mateo County bans tow operators from soliciting business at crash scenes and keeps tow trucks 500 feet away.

Tattoo and piercing shops in unincorporated San Mateo County need an annual LEA permit, and every practitioner must hold a current registration.

Since July 1, 2012, every massage practitioner working for compensation in unincorporated San Mateo County must hold current CAMTC certification, and every massage business must…

Retailers in unincorporated San Mateo County need an annual county Tobacco Retailer Permit for every location selling tobacco products.

Secondhand dealers and flea market operators in unincorporated San Mateo County must license with the County and hold purchased goods 15 days before resale.

The Director of Public Works may temporarily close County highways in unincorporated areas for block parties, celebrations and parades.

Any group meeting, rally, or similar gathering in a San Mateo County park needs a Parks and Recreation Department permit obtained at least ten days ahead under Section 3.68.140.

Under Ordinance Code Section 4.98.160(c), no tobacco retailer in San Mateo County's permit program may sell or offer for sale any Flavored Tobacco Product or Tobacco Product Flavor…

Cats and dogs over six months old in unincorporated San Mateo County must be spayed or neutered unless the owner instead obtains an unaltered-animal license or breeding permit under §…

In San Mateo County parks and the San Francisco Fish and Game Refuge, feeding, hunting, trapping or disturbing any wild bird or other wildlife is banned under the county's park rules.

Selling or offering cats, dogs or wolf hybrids on a public street, sidewalk or park in unincorporated San Mateo County requires a pet-sales business license under § 6.12.040(c), unless…

Unincorporated San Mateo County caps casual pet-keeping at four animals. Ordinance Code Section 6.20.020 makes it unlawful to keep five or more dogs, five or more cats, or five or more…

Unincorporated San Mateo County requires an annual license for every cat over three months old, with lower fees for altered cats and a lifetime tag.

Unincorporated San Mateo County R-1 lots may keep a small number of chickens and ducks by right, up to six on parcels of 2,500 sq ft or more, ten on parcels over 7,500 sq ft, but…

In unincorporated San Mateo County's C-1 Neighborhood Business Districts, a veterinary hospital for small animals needs a discretionary use permit before it can open, not just a…

No one may own or keep an exotic animal anywhere in unincorporated San Mateo County without a Health System use permit. Ordinance Code Section 6.08.030 requires prior approval from the…

Unincorporated San Mateo County has no breed-specific ban. The County Ordinance Code regulates individual dogs as dangerous or vicious based on behavior, not breed. California state…

Unincorporated San Mateo County requires every dog off its owner's enclosed property to be on a leash. Ordinance Code Section 6.04.060(a) bars any owner or caretaker from letting an…

Unincorporated San Mateo County properties must dispose of solid waste at least once a week and, where a hauler serves the area, must subscribe to that hauler's weekly collection…

Unincorporated San Mateo County treats illegal dumping as a misdemeanor and littering as an infraction, with major violations, mattresses, appliances, commercial quantities, drawing…

New commercial and mixed-use development in San Mateo County's CMU-1 (Commercial Mixed Use-1) zoning district, the unincorporated North Fair Oaks area, must build at least one refuse…

In the unincorporated Service Area, County Code Chapter 4.04 establishes mandatory minimum residential collection: garbage, recycling, and organics carts picked up once a week…

Single-family homes in San Mateo County's densely-populated unincorporated areas must subscribe to their hauler's organic waste collection service under Ordinance Code Sec. 4.04.140…

Recycling is part of the mandatory minimum residential service under County Code Chapter 4.04, with single-stream recyclables collected weekly alongside garbage and organics. The…

Unincorporated San Mateo County residents may set carts out no more than 24 hours before pickup and must store them out of sight within 24 hours after the hauler empties them.

In unincorporated San Mateo County, it is a misdemeanor to loiter in, on, or about any building or place open to the public where alcoholic beverages are sold. The Ordinance Code…

San Mateo County parks generally ban liquor other than beer or wine; hard alcohol is allowed only in designated areas of Coyote Point County Park under Section 3.68.080(t).

San Mateo County bans smoking, including e-cigarettes and vaping, throughout its unincorporated area and on every county-owned or leased building wherever located. Section 4.96.040(c)…

In unincorporated San Mateo County, hosting a loud or unruly gathering of four or more people where a minor drinks, uses cannabis, or is served alcohol triggers social-host liability…

In unincorporated San Mateo County, blocking a sidewalk or public right-of-way with an obstruction or excavation is declared a nuisance under Ordinance Code Chapter 1.12. The County…

Unincorporated San Mateo County requires a Public Works permit for fences, sidewalks, driveways or landscaping placed in the county right-of-way, and fines unpermitted encroachments…

In the unincorporated Midcoast (El Granada, Miramar, Moss Beach, Montara), county design review rules require new home exterior lighting to be directed away from neighbors and confined…

Development in unincorporated North Fair Oaks' CMU-1 commercial district must use dark-sky-compliant lighting confined to the property, and flood lights are banned absent a safety…

Unincorporated San Mateo County taxes one specific business category rather than classifying businesses generally: vehicle rental operators. Ordinance Code Section 5.150.040 charges…

Single-family organic waste generators in the county's densely populated unincorporated areas may compost yard and food waste on site instead of subscribing to hauler collection, per…

In San Mateo County's Design Review zoning districts, removing a protected tree requires planting at least three replacement trees of the same species, backed by a maintenance surety.

Unincorporated San Mateo County abates hazardous fire vegetation through its fire districts under California Health & Safety Code 14875 et seq. and Government Code 25845. Programs such…

Unincorporated San Mateo County does not ban or specifically permit-regulate artificial turf on private property, and the County's WELO governs water budgets without mandating or…

Unincorporated San Mateo County encourages native and drought-tolerant landscaping rather than mandating it for homeowners. The Countywide Water Pollution Prevention Program promotes…

Unincorporated San Mateo County requires new-development and open-area landscape plans to build in water-saving design under Ordinance Code § 4.36.120: plant choice, irrigation…

In unincorporated San Mateo County, pruning a Protected Tree generally does not need a permit, but a Protected Tree Pruning Permit is required to prune a Protected Indigenous Tree…

In the NMU-ECR District along El Camino Real in unincorporated North Fair Oaks, San Mateo County caps window signs at 25 percent of the window's glass area under Zoning Regulations…

County departments and staff are barred from using county resources to assist federal immigration enforcement absent a judicial warrant, under a countywide non-cooperation ordinance.

In the S-50 Combining District, layered onto R-2 (two-family) and R-3 (multi-family) parcels in unincorporated North Fair Oaks, San Mateo County requires a 20-foot front setback and a…

In the county's RH (Residential Hillside) zoning district, homes are capped at 28 feet measured from natural grade, with a lower 10-foot plate height for any part of a building that…

In the unincorporated North Fair Oaks S-50 combining district, buildings, accessory structures and raised patios or decks together cannot cover more than 50% of the lot.

Before San Mateo County issues a short-term rental permit in the unincorporated county, the owner must install smoke alarms complying with UL 217 in every bedroom, just outside each…

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…

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…

Possessing, selling, or exploding any fireworks is unlawful in unincorporated San Mateo County unless a Fire Warden permits a supervised public display.

San Mateo County Environmental Health posts a compliance placard at every inspected food facility under Ordinance Code § 4.56.070, and it is unlawful to operate without the placard…

Unincorporated San Mateo County property owners may not maintain a building, lot, vehicle or premises in a condition that lets rodents or other vermin breed or harbor there, under…

After a hearing finds repeated critical food-safety violations or unsafe staff practices, County Environmental Health can order a food facility to send all food-prep staff to an…

Unincorporated San Mateo County does not designate specific food truck vending zones but restricts operations through general zoning and parking rules. Food trucks may not vend from…

Unincorporated San Mateo County bans anyone from erecting, placing or maintaining a stand, vehicle, or any object on the public right-of-way of a county highway for peddling, under…

Mobile food facilities operating in unincorporated San Mateo County must obtain a Mobile Food Facility (MFF) permit from San Mateo County Health Environmental Health Services (EHS)…

By California state law (Health & Safety Code 1597.40-1597.46, as amended by SB 234), small and large family day care homes are a residential use by right in unincorporated San Mateo…

Unincorporated San Mateo County allows home occupations by right in residential zones like R-1 and R-E, but caps them at a quarter of the ground floor with no retail sales or outside…

Unincorporated San Mateo County bars youths under 18 from public places between 11 p.m. and 5 a.m. weeknights, midnight to 5 a.m. weekends, plus school hours, subject to listed…

San Mateo County Ordinance Code Section 4.72.140 requires every recycled water or graywater system to be designed and installed in accordance with California law and the local Plumbing…

Unincorporated San Mateo County requires the parcel owner to live in one unit whenever a junior accessory dwelling unit is built, secured by a recorded deed restriction.

San Mateo County waives development impact fees entirely for accessory dwelling units under 750 square feet, and for larger ADUs charges only a prorated share: Zoning Regulations…

San Mateo County bars accessory dwelling units built under its ADU chapter from short-term rental: Zoning Regulations Section 8.392.050(22) requires any ADU that is rented to be rented…

San Mateo County allows accessory dwelling units by right in the R-1, R-2, R-3, PC, CMU, NMU, R-E, RH, RM and TPZ districts and any other residential district under Zoning Regulations…

Converting an attached or detached garage into an accessory dwelling unit in unincorporated San Mateo County does not require replacing the lost parking spot: Zoning Regulations…

In unincorporated San Mateo County, a detached one-story accessory building in a residential district is capped at 30% of the rear yard, 1,000 square feet, and must sit at least 3 feet…

In unincorporated San Mateo County, building a swimming pool or spa requires a building permit and a boundary survey from the Planning and Building Department. Applicants submit plot…

Unincorporated San Mateo County follows California's Swimming Pool Safety Act for pool barriers. A qualifying enclosure must be at least 60 inches high, leave no more than a 2-inch gap…

In unincorporated San Mateo County, a Historic Preservation Permit is required before altering, demolishing or relocating any structure designated a County Historic Landmark or located…

Unincorporated San Mateo County grants residential developers a density bonus of up to 35 percent above the zoned maximum, plus incentives, parking reductions, or waivers, when a…

Commercial cameras in unincorporated county parks need a written permit from the Parks Director before shooting, with a news-gathering exemption.

Camping on public property in unincorporated San Mateo County is banned once an available shelter bed exists, backed by written-warning enforcement, a 72-hour removal notice, and…

Unincorporated San Mateo County's Agricultural Awareness ordinance declares normal farm impacts on neighboring property acceptable and routes disputes to a grievance committee instead…

New commercial development in North Fair Oaks' CMU-1 (Commercial Mixed Use-1) zoning district must plant street trees along any public sidewalk the project abuts, under Zoning…

Unincorporated San Mateo County charges a 10% transient occupancy tax on hotel stays of 30 days or less, collected by the operator.