Redwood City's Accessory Structures: The Rules That Matter

Every city handles accessory structures a little differently. In Redwood City, California, there are 6 distinct rules that residents and property owners should be aware of. Some are stricter than what neighboring cities enforce, and others are more relaxed. Here is what you need to know.

ADU Owner Occupancy

Redwood City requires the owner to live in either the main house or the junior accessory dwelling unit whenever a JADU is created; standard, larger accessory dwelling units carry no such owner-occupancy condition. A recorded deed restriction backs up the JADU rule and bars selling the JADU apart from the primary home.

Key details: Owner-occupancy: Required for JADUs only, not full ADUs. Owner may live in: Either main house or the JADU. Deed restriction: Recorded, bars separate sale of JADU. JADU size cap: 500 sq ft. JADUs per lot: 1 maximum.

An unrecorded deed restriction or a JADU operated without owner-occupancy, for example rented out while the owner lives elsewhere entirely, is a Zoning Ordinance violation the Zoning Administrator can pursue as a public nuisance and infraction under Article 50, with fines up to $100 for a first offense, up to $200 for a repeat within a year, and up to $500 after that, and each day of noncompliance a separate offense.

This is not one of those rules that cities tend to ignore. Redwood City actively enforces its adu owner occupancy requirements.

ADU Rules

Redwood City lets any residential lot with a single-family home add one accessory dwelling unit (ADU) and one junior ADU under Zoning Code Section 37.3. Standard ADUs cap at 850 square feet, rising to 1,000 square feet with more than one bedroom and 1,200 square feet for units meeting disabled-access standards. Only a 4-foot side and rear setback applies, no added parking is required, and ADUs are exempt from the lot's overall coverage limit.

Key details: Governing section: Zoning Code Sec. 37.3. Standard ADU size cap: 850 sq ft. Multi-bedroom ADU cap: 1,000 sq ft. Detached ADU height: 20 ft flat / 24 ft pitched. Required setback: 4 ft side and rear.

ADUs built without a complying permit are enforced the same as any other zoning violation. Under Article 50, a noncompliant structure is declared a public nuisance (Sec. 50.2), any permit issued in conflict with the Zoning Code is void, and the Zoning Administrator, under the Planning Director, can cite violators. Section 50.5 makes each violation an infraction: up to $100 for a first offense, $200 for a second within a year, and $500 for each further violation of the same provision, with each day counted as a separate offense.

Shed & Carport Rules

Redwood City limits sheds, detached garages and other accessory buildings to 16 feet in total height, with a 9-foot wall cap on flat or shed roofs near the side and rear lines. They must sit at least 4 feet off the side and rear property lines and 6 feet from any other building on the lot.

Key details: Max total height: 16 feet. Max wall height (flat/shed roof): 9 feet near side/rear line. Side and rear setback: 4 feet. Setback from other buildings: 6 feet. Small shed exception: under 120 sq ft, no foundation, 7 ft max.

A shed or accessory building that breaks Section 36.5 is declared a public nuisance under Section 50.2. Under Section 50.5 a violation is an infraction punishable by a fine up to $100 for a first offense, up to $200 for a second violation of the same rule within a year, and up to $500 for each further violation, with each day of a continuing violation a separate offense. The Zoning Administrator issues citations, and the City Attorney can sue to compel removal.

Garage Conversions

Redwood City lets homeowners convert an existing garage into an accessory dwelling unit with no added setback, and under the Statewide Exemption path, no discretionary review: only a building permit is required, and the converted space can expand by up to 150 square feet for a proper entrance.

Key details: Added setback for conversion: None required. Statewide Exemption path: Building permit only, no discretionary review. Expansion allowance: Up to 150 sq ft for entrance. Ministerial review deadline: 60 days. Fire-safety setback: Still required.

Converting a garage without the required building permit, or exceeding the 150-square-foot expansion allowance for entrance access, is a Zoning Ordinance violation the City enforces under Article 50 as a public nuisance and infraction, punishable by fines up to $100 for a first offense, up to $200 for a repeat within a year, and up to $500 after that, each day counted separately.

ADU Impact Fees

Redwood City charges no impact fees on any accessory dwelling unit or junior ADU smaller than 750 square feet. Above that size, impact fees are charged proportionately to the ADU's square footage relative to the primary dwelling, and utility connection fees and capacity charges are not counted as "impact fees" at all.

Key details: Fee exemption threshold: Under 750 sq ft. 750 sq ft or larger: Proportional fee to primary dwelling. Excluded from "impact fees": Utility connection and capacity charges. Prerequisite: Adequate water/sewer service confirmed. Standard ADU cap: 850 sq ft (1,000/1,200 with exceptions).

There is no separate penalty tied to § 37.3(K) itself; the consequence of misapplying it is a fee dispute handled administratively through the building permit process, and any ADU built without adequate water or sewer service, or that evades a properly calculated proportional fee, is treated as a Zoning Ordinance violation subject to Article 50's infraction fines of up to $100 to $500 per offense, with each day a separate violation.

If you are coming from a city with tighter rules, you will find Redwood City gives residents more flexibility on adu impact fees.

ADU Rental Restrictions

Redwood City bars owners from selling an accessory dwelling unit or junior ADU separately from the main house, and from renting either one for less than 30 days, under Zoning Code Section 37.5. Only ADUs already registered as short-term rentals with the City before January 1, 2020 are grandfathered in and may keep operating as short-term rentals.

Key details: Governing section: Zoning Code Sec. 37.5. Minimum rental term: 30 consecutive days. Separate sale of ADU: Prohibited. Grandfathered short-term rentals: Registered before Jan. 1, 2020. JADU occupancy rule: Owner must live in home or JADU.

Operating an ADU as an unregistered short-term rental or attempting to sell one separately violates Section 37.5 and is enforced under Article 50 like any other Zoning Code breach: the use is declared a public nuisance (Sec. 50.2), and Section 50.5 makes it an infraction punishable by up to $100 for a first violation, $200 for a second within a year, and $500 for each subsequent violation of the same provision, with the Zoning Administrator authorized to issue citations.

Compared to other cities, Redwood City takes a harder line on adu rental restrictions. The enforcement and penalty structure reflects that.

The Bottom Line

Redwood City is tougher than many cities when it comes to accessory structures. Out of the 6 rules covered here, 2 are rated strict. If you are a homeowner, renter, or business owner in Redwood City, take the time to understand these requirements before they become a problem. Most violations come with fines, and some repeat violations can escalate.

This guide is based on Redwood City's current municipal code. Local rules can and do change, so check the individual ordinance pages for the latest details, penalties, and FAQs.