Key Facts Ordinance Text Full Breakdown Violations FAQ Sources More in Redwood City

Redwood City, CA Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

ADU rules in Redwood City, CA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

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
Parking required: None
Permit review timeline: 60 days, ministerial

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in California under recent ADU streamlining laws. The Redwood City, CA rules below cover local size, height, and setback requirements.

Summary

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.

A four (4) foot side and rear yard setback shall be required. Accessory dwelling units shall be subject to front yard setbacks applicable to the primary dwelling unless such a requirement would preclude the construction of a Statewide Exemption Accessory Dwelling Unit as is described in Section 37.4.B. ... Accessory dwelling units detached from an existing or proposed primary dwelling shall be subject to a maximum height of twenty (20) feet when the accessory dwelling unit has a flat roof, or twenty-four (24) feet when such unit has a pitched roof (with the additional four (4) feet solely devoted to roof pitch. ... Standard Units. Accessory dwelling units shall not exceed eight hundred fifty (850) square feet, except as specified in subsections (b) and (c) below. Multiple Bedroom Units. Accessory dwelling units that include more than one (1) bedroom shall not exceed one thousand (1,000) square feet. Accessible Units. Units meeting the California Building Code requirements for disabled access are permitted to have up to one thousand two hundred (1,200) square feet.

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Zoning Code: Supplement 29 | City Code: Supplement 61 Update 1).

Full Breakdown

3 of the Zoning Code sets the development standards for accessory dwelling units (ADUs) and junior ADUs (JADUs) in Redwood City's residential, mixed-use, and residential-allowing precise plan districts. A single-family lot may hold one ADU and one JADU; a duplex or multifamily lot may add two detached ADUs, plus conversion of up to 25% of existing units from non-livable space like basements or garages. ADUs and JADUs do not count toward the lot's allowed density. Setbacks are just 4 feet on the side and rear, with no setback at all for a unit built inside existing living area or a legal accessory structure being converted, provided fire-safety clearances are met.

Attached ADUs that stay within the primary dwelling's setbacks follow the underlying district's height limit; those that encroach into the setback are capped at 20 feet with a flat roof or 24 feet with a pitched roof, the same ceiling that applies to detached units. Detached ADUs also cannot put more than 600 square feet above the first floor, and balconies, decks, and open stairways must face away from adjacent side and rear yards. 4, which allows up to 800 square feet. No additional or replacement parking is required.

Impact fees are waived entirely for ADUs and JADUs under 750 square feet, and units 750 square feet or larger are charged fees proportional to the primary dwelling's square footage. 6, the Director must approve or deny a complete ADU building permit application ministerially within 60 days.

Violations & Fines

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.

Frequently Asked Questions

Do I need a discretionary permit to build an ADU in Redwood City?

No. Section 37.6 makes ADU review ministerial: once your building permit application is complete, the Director must approve or deny it within 60 days based only on compliance with Section 37.3's standards, with no public hearing or use permit involved.

How large can my accessory dwelling unit be?

Standard ADUs are capped at 850 square feet under Section 37.3(C)(5). That rises to 1,000 square feet if the unit has more than one bedroom, and to 1,200 square feet for a unit that meets California Building Code disabled-access requirements.

Do I need extra parking for an ADU?

No. Section 37.3(D) states no additional parking spaces are required for an ADU or junior ADU, and no replacement parking is required even if an existing garage or carport is demolished to build the unit.

What setback does my ADU need from the property line?

Just 4 feet on the side and rear under Section 37.3(C)(1)(a). No setback at all applies if the ADU is built inside existing living area or an existing accessory structure, as long as fire-safety clearances are met.

Sources & Official References

[1]Redwood City Zoning Code, Article 37 (Municode)

Other rules in Redwood City

Parking Rules: Overnight ParkingSome Restrictions Parking Rules: Street Parking LimitsSome Restrictions Shed & Carport RulesSome Restrictions Parking Rules: RV & Boat ParkingSignificant Restrictions ADU Owner OccupancySignificant Restrictions Garage ConversionsSome Restrictions ADU Impact FeesLight Restrictions ADU Rental RestrictionsSignificant Restrictions Noise Ordinances: Amplified Music & Outdoor SoundSome Restrictions Parking Rules: EV ChargingSome Restrictions Parking Rules: Commercial & Oversized VehiclesSignificant Restrictions

All Redwood City rules

How Redwood City compares: Easiest Cities to Build an ADU·California rules heatmap·Compare Redwood City to another location·View the California accessory structures overview

See something wrong?

Help us keep this page accurate. If you notice an error or outdated information, let us know.

ADU Rules in Nearby Cities

How other cities in San Mateo County handle adu rules.

Daly City, CA