Accessory Dwelling Units

ADU Development Steps

An Accessory Dwelling Unit can be either new construction, or a conversion of an existing structure.

Step One: Contact Planning to confirm that the property is eligible for ADU development. Call 562-989-7340 or email commdev@cityofsignalhill.org 

Step Two: Conduct methane testing as per Signal Hill Municipal Code Chapter 16.24.080. Please reference the Project Development Guide section on Methane Assessment. This will include a deposit of $3500 to pay for consultant reviews of the work plan, testing report, and mitigation measures. Methane assessment permit fees are separate from the deposit.

Step Three: Submit construction plans, including methane mitigation plans, for review. Please go to the Building Permits portal to submit a permit application and plans: https://signalhill.portal.iworq.net/portalhome/signalhill 

If the ADU is new construction of 500 square feet or more, it will require a Low Impact Development plan for stormwater pollution control. Contact Public Works Engineering for more information: PublicWorksEngineering@cityofsignalhill.org

Basic Summary of ADU Standards

For a full list of ADU standards, please see the Project Development Guide section on ADUs.


NUMBER OF UNITS ALLOWED

ADUs on Lots with Single-Family Dwellings

  • A maximum of one ADU, and one Junior ADU (JADU) may be allowed on a lot with one or more existing or proposed single-family dwellings. However, in order to have both, the ADU must be new construction and must be detached. A JADU is not permitted on a lot with more than one single-family dwelling. 
  • If the ADU is proposed within an existing accessory structure, the ADU may add up to 150 square feet (SF), but only for the purpose of providing ingress/egress. (Any larger expansions would trigger provisions of the local jurisdictions ordinance if one exists).
  • A maximum 16’ height limit may be required (especially if existing views of neighboring properties are impacted).        
  • A minimum of 4’ side and rear yard setbacks from property line are required for any new ADU that is not converted from an existing structure, or for any new structure constructed in the same location and to the same dimensions as the existing structure.

ADUs on Lots with Multi-Family Dwellings

  • The total number of ADUs allowed is no more than 25% of the total number of existing multi-family units on the lot (example: 4 existing MFD units on a lot = 1 ADU max; 7 existing MFD units on a lot = 1 ADU max; 8 existing MFD units on a lot = 2 ADUs max). (JADUs are only allowed in single-family units per GC 65852.22.) A minimum of one ADU is allowed within an existing multi-family structure structure in areas not used as livable space, including (but not limited to) storage rooms, boiler rooms, passageways, attics, basements, or garages.
  • A maximum of twodetached ADUs are allowed on a lot with an existing multi-family structure and are subject to a height limit of 16’ and 4’ side and rear yard setbacks. Detached ADUs may be attached to each other. They may be new construction or converted accessory structures.

 JUNIOR ACCESSORY DWELLING UNITS

The City must ministerially approve an application to create a JADU within a single-family dwelling provided it meets all the following requirements:  

  • The JADU is limited to 500 SF and must be contained within the walls of an existing or proposed single-family residence.
  • The JADU must have independent exterior access from the existing residence.
  • The JADU must have a kitchen with provisions for cooking. Full size kitchen appliances are not required.
  • The JADU is not required to have a dedicated bathroom.

City of Signal Hill Pre-Approved Standard ADU Plan Program

Program Overview

The City of Signal Hill’s Pre-Approved Accessory Dwelling Unit Plans Program provides applicants the opportunity to utilize pre-approved plans designed by private licensed architects and engineers. The plans have been reviewed and pre-approved by Signal Hill Community Development for compliance with the Building, Residential, and Green Codes.


Design Firm Submittal

For licensed professionals interested in submitting plans in for approval of pre-approved plans, submit plans to online portal system: https://signalhill.portal.iworq.net/SIGNALHILL/new-permit/601/2731

 

Pre-Approved Plans

The following plans have been pre-approved by the Signal Hill Community Development Department. These pre-approved plans are designed and owned by the listed design firms and may be purchased directly from the plan owner. Please note that these pre-approved plans may not be approved for use in certain situations and/or site conditions. The City of Signal Hill does not endorse the utilization of any of the listed plans.

 

Methane Assessment

Prior to submittal of standard pre-approved plans for a construction permit, a methane assessment is required of all properties within the City of Signal Hill. Methane assessment is required to determine appropriate methane mitigation measures. If mitigation measures are required, the approved and stamped methane mitigation design plan will need to be attached to the pre-approval plan submittal. For questions regarding this requirement, please contact the Community Development department at (562) 989-7340 or commdev@cityofsignalhill.org.


The City has not received any submissions for pre-approved plans yet.  Please check back later.