Castro Valley HOA Guide: County Rules for Boards and Owners

County Code Chapter 6.74 prohibits smoking in and around multi-unit residences. It has applied since July 1, 2022 to lots inside the county’s urban growth boundary, and it covers condominium complexes and townhomes attached to a unit on the next lot.

• Inside units (section 6.74.040): no smoking in any unit, including a private balcony, porch, deck or patio. Cannabis and electronic smoking devices count.
• Common areas (section 6.74.050): no smoking unless the association sets up a designated area that is unenclosed, at least 25 feet from doors, windows and play areas, and no more than 10% of the property’s unenclosed area.
• Signs and notices (section 6.74.080): whoever controls the common area must post no-smoking signs. Sellers must give buyers written notice of the rule before a sale.

The county cannot fine anyone until the public health department has given that person at least three warnings. After that, fines are $100, $200 and $500 for a first, second and third violation within three years (section 6.74.110).

We could not find a short-term rental permit program for unincorporated Alameda County. The county code has no short-term rental chapter in its business or zoning titles, and the Planning Department’s website lists none among its proposed ordinances. Do not read that silence as permission: call Planning at (510) 670-5400 to ask what the zoning of the lot allows.

An ADU may only be rented for terms longer than 30 days (section 17.55.130). Your CC&Rs can go further than the county: California Civil Code section 4741 limits how far an association can restrict rentals generally, but it does not stop an association from prohibiting rentals of 30 days or less.

For longer leases, county tenant protections bind owners who are landlords, including owners inside an HOA:

• Just cause eviction (Chapter 3.70): passed on February 4, 2025. After a tenant has lived in a unit for 12 months, the landlord needs one of the just causes in state law to end the tenancy and must file the termination notice with the county within three days of serving it. Ask the county’s Housing and Community Development Department whether a rented condo or townhome is covered.
• Mediation (Chapter 3.68): a tenant in any rental dwelling can ask for mediation within 21 days of a proposed rent increase of more than 5%.
• Not adopted yet: county staff told a Board committee on February 26, 2026 that a rental registry was in development. We did not find a rent cap in the county code.

The county’s ADU rules are in Zoning Ordinance Chapter 17.55, last amended by Ordinance 2026-1 in January 2026. A detached ADU can be up to 850 square feet with one bedroom or less and 1,200 square feet with two or more. Junior ADUs are capped at 500 square feet. Detached units are generally limited to 16 feet in height with 4-foot side and rear setbacks. ADUs must be rented for more than 30 days at a time.

For boards, the state rule matters more than the county one. Civil Code section 4751 voids CC&R provisions that prohibit or unreasonably restrict an ADU or junior ADU on a lot zoned for single-family use. An association can still apply reasonable restrictions through its architectural review process.

On private property, the county’s Neighborhood Preservation Ordinance (Chapter 6.65) sets the vehicle rules, and Code Enforcement applies them:

• Paved surfaces only (section 6.65.030): vehicles, RVs, trailers and boats may not be parked or stored on anything other than a driveway or parking area of concrete, asphalt or a similar all-weather surface.
• Inoperable vehicles: a vehicle that is wrecked, dismantled or inoperable for more than 48 consecutive hours counts as broken, and keeping one on the property is a nuisance.
• Fines: the first letter for a parking violation carries no fine. The second, third and later letters carry $100, $200 and $400.

On public streets, the county traffic code (Chapter 10.04) prohibits using a street to store vehicles. We could not open that section to confirm its time limit, so we do not quote one. Code Enforcement says abandoned vehicles on the street go to the Sheriff’s Office. If your association owns its streets, parking is governed mainly by your own rules and by state towing law.

Water comes from the East Bay Municipal Utility District (EBMUD), not the county. Section 29 of EBMUD’s regulations, in the version dated July 1, 2026, prohibits these uses of drinking water, so give the list to your landscape contractor in writing:

• Watering so that more than incidental runoff flows onto the next property, a sidewalk or the street.
• Watering during measurable rain or within 48 hours after it.
• Washing down sidewalks and driveways.
• Irrigating nonfunctional turf, meaning ornamental lawn, on commercial, industrial and institutional properties.

Two points matter for the budget. First, EBMUD’s lawn conversion rebate pays $1 per square foot, or $2 for a project that sheet mulches the lawn and uses mostly California native plants. Rebates are capped over any 24 months at $15,000 for commercial and large multi-family accounts and $2,000 for residential accounts, so ask EBMUD which cap applies to your common-area meter. Work cannot start until EBMUD approves the project. Second, a state law passed in 2023 (AB 1572) will bar the use of drinking water on nonfunctional turf in HOA common areas starting January 1, 2029. The rebate can pay for part of a conversion a board will have to make anyway.

On owners’ lots, Civil Code section 4735 prevents an association from banning low-water plants or artificial turf as a replacement for lawn.

Chapter 12.11 covers trees in the county right-of-way, the strip between the property line and the edge of the paved street. The adjacent property owner must plant, maintain, remove and replace those trees, no matter who planted them (section 12.11.120). Where the frontage is common area, that owner is the association.

• Permit first: planting, pruning or removing a right-of-way tree requires an encroachment permit from the Public Works Agency.
• Licensed contractor: the work must be done by a contractor with a C27 or C61/D49 license unless Public Works agrees otherwise in writing.
• Penalties: topping is prohibited, and a violation can bring a civil penalty of up to $1,000.

Sidewalks follow the same logic. Under Chapter 12.13, the owner of the lot fronting a sidewalk must repair it and is liable to anyone injured by a failure to do so. We did not find a county chapter that protects trees on private lots.

The Neighborhood Preservation Ordinance treats overgrown property as a public nuisance. Section 6.65.030 calls for grass and weeds to be cut to six inches or less, tree limbs within 100 feet of a building to be trimmed up six feet from the ground and roofs kept clear of leaves. Trash carts may not sit in a front yard, driveway or street for more than 24 hours in any seven days.

If an owner does not comply, and that includes an association that owns open space, the county can hire a contractor and bill the owner. An unpaid bill becomes a lien collected with the property tax bill.

For wildfire, the Board of Supervisors adopted the State Fire Marshal’s fire hazard severity zone map for the unincorporated area in June 2025 (Chapter 6.05). The Alameda County Fire Department inspects defensible space in very high zones, in three bands: 0 to 5 feet, 5 to 30 feet and 30 to 100 feet from the building. It says the inspection is free. Look up each common-area address on the state’s zone locator, and call the defensible space line at (510) 632-3473, extension 1722.

The Castro Valley Sanitary District requires a Sewer Lateral Compliance Certificate before the close of escrow when property inside the district is sold (Ordinance No. 179, in effect since July 1, 2019). A certificate lasts 10 years after a passed camera inspection and 30 years after a full replacement.

The district’s page does not say how the rule works where several units share one lateral or the association owns the line. A condo or townhome board should ask the district at (510) 537-0757, then tell owners who handles the inspection when a unit sells.

Under the county noise ordinance, Chapter 6.60, construction noise is exempt from 7 a.m. to 7 p.m. on weekdays and 8 a.m. to 5 p.m. on Saturday and Sunday. In residential areas, leaf blowers, mowers and similar power tools that can be plainly heard 50 feet away may not run between 7 p.m. and 7 a.m. on weekdays or between 7 p.m. and 8 a.m. on weekends.

Put those hours in your landscape and construction contracts. Your own rules can set shorter hours. The chapter also prohibits frequent or continuous animal noise that can be plainly heard 50 feet away.