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Fountain Valley ADUs

Everything about building Accessory Dwelling Units in Fountain Valley, CA

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400 sqft

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The city government of Fountain Valley has updated its local zoning codes to comply with the State ADU mandate.
The California Building Code (CBC) 2019 is adopted.

Last Updated 08/14/21


City Hint: The City of Fountain Valley permitted a total of 50 ADU projects in the past year of 2020.

Number of ADUs allowed:

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

Types of ADUs allowed:

Detached ADU, Attached ADU, Junior ADU are allowed. 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 Accessory Dwelling Units by ordinance or of the underlying zoning district. ~ AB68

ADU size:

Single-family and multi-family Parcels will be approved to add up to 850 sq. ft. for a one bed ADU or up to 1,000 sq. ft. for a two bed ADU, regardless of the underlying zoning standards of the property. A Junior Accessort Dwelling Unit (JADU) up to 500 sq. ft. is approved. The minimum size of any living unit (including Accessory Dwelling Unit (ADU)s and Junior Accessort Dwelling Unit (JADU)s) is 150 sq. ft. according to California Residential Code. ~ According To AB68


The maximum required setback for a detached new construction ADU shall be no more than 4 feet from the rear and side property lines. Setbacks will not be required for ADUs and JADUs converted from existing space that was legally eastablished. Attached ADUs and conversions from existing space to be expanded will be required to comply with the setbacks of the underlying zone. ~ AB68 & AB881 Update


Lots which convert an existing garage to an Accessory Dwelling Unit or Junior ADU will not be subject to replacement parking requirements. ~ Updated: State Law AB-68

Fire Safety:

Fire Sprinklers. Fire sprinklers are not required if they are not required for the primary dwelling. The side and REAR setbacks shall be sufficient for fire safety.

Shape, materials and style:

Be compatible with, and made structurally a part of the main structure (e.g., share a common wall with the main structure, rely partially on the main structure for structural support or be attached to the main structure). Be compatible with the materials and color of the main structure whenever feasible. Detached accessory structures shall be compatible with the materials and color of the main structure whenever feasible.


Maximum Allowed Height of Structures. See also Section 21.18.050 (Height measurement and height limit exceptions). No architectural features, windows, etc., above the second story eave line. Maximum wall height of ten feet for first story area used to meet seventy percent ratio requirement. The square feet of any vaulted ceiling area above the ten foot wall height shall be counted toward the second story area when calculating the seventy percent second to first story ratio.

Design review:

Government Code to requires local jurisdictions to ministerially consider accessory dwelling units and junior accessory dwelling units without a public hearing. Review. The review of an application for a density bonus and concession or incentive request shall be processed as a planning application pursuant to Chapter 21.32 of the Municipal Code. The planning department shall review the application for its conformance with California Section 65915 et seq., and applicable city codes and make a report to the planning commission. If the application involves a request for direct financial incentives, then any action by the planning commission on the application shall be advisory only, and the city council shall have the authority to make the final decision on the application. Building Permit. Prior to constructing an accessory dwelling unit within an existing structure, the applicant must apply for a building permit. The application shall be ministerially reviewed for compliance with-all requirements imposed by section (a).", " Plan Review. The City shall consider an application for a building permit for an accessory dwelling unit under section (a) within 120 days of submittal of a complete building permit application, unless tolled due to corrections being issued by the city. The City's reviewperiod shall begin to run when a complete building permit application and plans are first formally submitted and shall be tolled when corrections are issued by the City. Tolling shall begin again upon formal re-submittal of the plans to the City.

Number of Bedrooms:

Not specified by State Standards.


Between between 2020 and 2025, owner occupancy requirements will not apply to new Accessory Dwelling Units. (applicable to new construction and conversion units) ~ According To SB13

Utility connections:

Utility Connections. accessory dwelling units shall not be considered by the city to be a new residential use for the purposes of calculating connection fees or capacity charges for utilities, including water and sewer service. The city may require the applicant to install a new or separate utility connection directly between the accessory dwelling unit and the utility. Consistent with California Government Code Section 66013, the connection may be subject to a connection fee or capacity charge that shall be proportionate to the burden of the proposed accessory dwelling unit, based upon either its size or the number of its plumbing fixtures, upon the water or sewer system.

Historic Requirements:

If the accessory dwelling unit is located within an architecturally and historically significant historic district, additional review may be required.


Passageway and Entrances. No passageway shall be required in conjunction with the construction of an accessory dwelling unit. Entrances and outside stairways serving second story accessory dwelling units shall not be constructed on any building elevation facing a front or side yard public street. Landing areas for outside stairways shall be screened from adjacent side and rear yard properties when adjacent to other single-family homes and cannot be visible from a front or side yard public street. Landing areas that are covered with a roof structure shall be counted toward the 70% ratio if attached to the main dwelling. Outside stairways shall adhere to setback requirements of this code. Only one entrance/exit point shall be provided with a door, or sliding glass door, per each accessory dwelling unit. No entry to a ground level accessory dwelling unit shall be visible from the public right-of-way. The method of screening of any landing or entry shall be architecturally compatible with other onsite development in terms of colors, materials, and architectural style. Entrance. A junior accessory dwelling unit must have a separate entrance from the main entrance to the structure, with an interior entry to the main living area. A permitted junior accessory dwelling may include a second interior doorway for sound attenuation but must still be accessible.

Rear Yard Coverage:

A minimum of one thousand square feet shall be maintained as rear yard open space for single-family detached uses.

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. ***

Residential Building Code:

The California Building Code (CBC) 2019 is adopted.

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