Statewide Update: New California ADU Bills AB68, SB13, AB881, AB670 have passed. These laws create more options for building an ADU in 2020. Use ADU Services to learn how they affect your property!

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Redwood City ADUs

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PLANNING OFFICE The city planning office remains open at this time and is accepting inquires and permit applications.

The city government of Redwood City will approve ADUs under California's statewide mandated regulations.
The California Building Code (CBC) 2019 is adopted.
Relevant state bill updates for SB13, AB68, AB881, AB670 are shown in green below.

Last Updated 03/27/20


City Hint: The city has not yet responded to requests for ADU permit volumes for the past year, but they will be provided here once response has been received.


Number of ADUs allowed:

Under state law, each single-family home may now build at least one Accessory Dwelling Unit (ADU). Owner occupied single-family lots may build one Accessory Dwelling Unit (ADU) and one JADU. Multi-family lots, per every four existing residential units, may build one Accessory Dwelling Unit (ADU), so long as the existing units were legally established.

As of January 1st, 2020

Types of ADUs allowed:

Detached ADU, Attached ADU, Junior ADU are permitted. ADUs may be new construction or converted from existing space. JADUs must be converted from existing space.

Lot size:

Residential parcels will not be subject to any minimum lot size for ADUs by ordinance or of the underlying zoning district. ~ Updated: State Law AB-68

As of January 1st, 2020

ADU size:

Single-family and multi-family Properties will be allowed to add up to 850 square ft. for a one bed ADU or up to 1,000 square ft. for a two bed ADU, regardless of the underlying zoning standards of the property. A Junior ADU up to 500 square ft. is allowed. The minimum size of any living unit (including ADUs and Junior ADUs) is 150 square ft. according to Califronia Residential Code. ~ Updated: State Law AB-68

As of January 1st, 2020


The maximum required setback for a detached new construction Accessory Dwelling Unit (ADU) shall be no more than 4 ft from the rear and side property lines. Setbacks will not be required for Accessory Dwelling Unit (ADU)s and Junior Accessory Dwelling Units converted from existing space that was legally eastablished. Attached Accessory Dwelling Unit (ADU)s and conversions from existing space to be expanded will be required to comply with the setbacks of the underlying zone. ~ AB-68

As of January 1st, 2020


Parcels which convert an existing garage to an Accessory Dwelling Unit (ADU) or JADU will not be subject to replacement parking requirements. ~ AB-68

As of January 1st, 2020

Fire Safety:

Fire sprinklers shall be installed for the ADU.

Shape, materials and style:

An accessory dwelling unit shall be architecturally compatible with the architectural style and exterior paint and materials of the single family dwelling on the same lot.


Maximum building height is 28 feet and structures shall not exceed 2.5 stories. The building height of a detached accessory dwelling unit shall not exceed the building height of a single-family dwelling on the same lot.

Design review:

Ministerial review process.

Number of Bedrooms:

Up to one (1) bedroom shall be permitted.


Owner-occupancy will not be required for new Accessory Dwelling Unit (ADU)s (conversion and new construction) built between 2020 and 2025. ~ SB13 Update

As of January 1st, 2020

Utility connections:

shall be exempt from the requirement of upgrading a water main.

Permit Fees

SB13 Update: As of January 1st, 2020, local impact fees for ADUs will be reduced substantially statewide.


An accessory dwelling unit, commonly known as a second unit or in-law unit, is an attached or detached dwelling unit that is located on the same lot as a single family dwelling and provides complete living, sleeping, eating, cooking, and sanitation facilities
separate and independent of the main dwelling.


For lots that are greater than or equal to 10,000 square feet in the Residential Hillside (RH) or Residential Single-Family (R-1) Zoning Districts, the maximum allowable floor area for an ADU shall be 800 square feet and no more than two (2) bedrooms.

The homeowner may live offsite and rent out both the main house and the ADU due to:
a. A medical condition that requires residency elsewhere; or
b. The homeowner accepts a job transfer outside of the San Francisco Bay Area.

A detached ADU may be built within a required rear yard setback area provided that the ADU meets the following requirements:
a. Minimum Rear Yard Setback: 10 feet
b. Maximum Building Height: 14 feet
c. Maximum Wall Height: 9 feet
d. No more than 50% of the required rear yard setback area shall be covered by structures.

Allowed Zones:

*** Beginning in 2020, according to state law, all residential zoning districts, including single-family and multi-family, are allowed to build Accessory Dwelling Units. ***

An Accessory Dwelling Unit (ADU) may be built on the same property as an existing or proposed single-family residence in the RH, R-1, R-2, R-3, R-4, and R-5 zoning districts.

As of January 1st, 2020

Open Space:

The front yard shall be subject to the minimum pervious area and stormwater requirements of the underlying zoning district.

Lot Coverage:

Total lot coverage is limited to 40 percent of the lot area. Not more than 40 50 percent of the required rear yard shall be covered by any combination of accessory buildings or an accessory dwelling unit subject.

Residential Building Code:

The California Building Code (CBC) 2019 is adopted.

Redwood City City Planning Offices

Redwood City Planning Division

Contact Planner Diana O'Dell. Counter Hours: 8AM-5PM (M/W/F), and 12:30PM-5PM (T/Th) (walk-ins welcome)

1017 Middlefield Road Redwood City, CA 94063

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Nikki James

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Redwood City ADU Marketplace

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Costs / ROI


* upon completion of ADU


* based on local average price per sqft


* estimated by location


* 30 years / 5% interest rate / 20% down payment


Appreciation Estimate = (Base Value: $) / (Home's Living Space: sqft) * (ADU's Living Space: sqft)

Rental Estimate = (Rent Per Sqft: $5.24) * (ADU's Living Space: sqft)

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