Number of ADUs Allowed in Signal Hill
- Maximum size: 1,200 sq ft (detached or attached, or 50% of the size of the main dwelling)
- Side/rear setbacks: 4 feet
- Two story: Yes, for both attached and detached ADUs
- Building separation: 6 feet
- Soils Report: Possibly, especially in areas with grading or on hillsides
- Building Verification Survey: Yes
- Coastal permit (in some areas): N/A
- Stormwater Mitigation: Yes
Number of ADUs Allowed in Signal Hill
You are allowed to put one attached or detached ADU on single-family property in Signal Hill, as well as one JADU.
Multifamily property owners in Signal Hill may convert existing uninhabitable space into at least one attached ADU, and additional ADUs not to exceed a maximum number equal to 25% of the existing units. Ergo:
- From 2 to 7 units, you could convert existing uninhabitable space into one ADU
- From 8 to 11 units up to 2 ADUs
- From 12 to 15 units up to 3 ADUs
- And so on.
No more than two detached ADUs may be constructed on a multifamily lot in Signal Hill.
ADU Signal Hill – Size & Building Constraints
A detached ADU can be up to 1,200 square feet in Signal Hill.
An attached ADU in Signal Hill can be up to 1,200 square feet, or 50% of the square footage of the primary dwelling unit, whichever is smaller.
An attached or detached ADU can be up to 16 feet tall in Signal Hill.
Due to the 16-foot height restriction, 2-story ADUs are generally not permitted in Signal Hill.
No, height restrictions on detached ADUs in Signal Hill generally prevent two ADUs from being stacked one on top of each other (one on each story of a two-story building). Single-family property also limits you to one detached ADU on the property, which would also eliminate the option of two stacked detached ADUs.
Yes, you can build two ADUs attached to each other on one separate detached structure in Signal Hill. Keep in mind that only multifamily property is eligible, since multifamily property can have up to two detached ADUs and single-family property is limited to one detached ADU.
No, a JADU is defined as an ADU converted from existing space within the main structure of the primary dwelling unit. As such, it cannot be attached to an ADU.
Generally roof decks would be permitted on an ADU, but must meet the height restrictions for the zone. Roof decks cannot encroach into the required setbacks. As a rule of thumb, railings and access staircases above 42″ need to be included in height calculations.
An ADU must match or harmonize with the exterior of the main dwelling unit, including color palette, roof pitch, architectural style, and other aesthetic characteristics.
ADU Setbacks in Signal Hill
ADUs behind the primary dwelling unit in Signal Hill require a minimum of 4-foot side and rear setbacks.
No specific building separation requirements are specified in Signal Hill. 6-foot building separation is common throughout California due to fire codes and other regulations, but we will need to check the requirements based on the zoning of your specific property during the planning stage.
ADUs are generally not allowed in the front yard of property in Signal Hill.
ADU Setbacks in Signal Hill
No, ADU building plans must be submitted to the Community Development Department online via thedepartment’s web portal.
Signal Hill may require a soils report for ADU permitting to make sure the soil can support the new structure, especially if the ADU will be located on a hillside, an area with significant grading, or if there are special foundation requirements.
Sufficient green space and permeable surface must be maintained on the property. City regulations do not specify specific percentages and must be approved on a case-by-case basis in the planning stage.
The plan check process for an ADU in Signal Hill involves the following steps:
- Eligibility check
- Methane testing
- Submission of plans
- Plan check by Building Safety program
- Permit issuance
- Inspection
The plan check usually takes about 4-6 weeks, while the permit issuance process can take up to an additional 2-4 weeks.
Parking for Signal Hill ADU
One new parking spot is typically required to be added to the lot per new ADU. However, exemptions may apply if:
- The ADU was built into an existing structure.
- The property is located within a historic district.
- The property is located within ½ mile walking distance of a public transportation stop.
- The property is located within one block of an established vehicle share stop.
- Off-street parking permits are required but not offered to ADU occupants.
If a parking space must be added, it can be included on the driveway or any setback areas, and it may be configured as tandem parking.
Additional Requirements in Signal Hill
Per Title 24 of the California Energy Code, solar panels of appropriate size and capacity are mandatory on new-construction ADUs. ADUs built from converted existing structures are exempt, as may be ADUs located under significant shading. Smaller ADUs may be subject to reduced or modified solar panel requirements.
An ADU is not required to have a separate water or electrical meter. You can opt for the ADU to share service with the main dwelling unit. However, you can request separate water or electrical meters from the City of Signal Hill.
ADUs usually do not get their own separate address in Signal Hill.
Low Impact Development (LID) is an approach to land development or redevelopment that seeks to preserve and conserve onsite water quality and natural features, with minimal detrimental effect to local waterways and ecosystems. The City of Signal Hill requires LID fees for ADUs larger than 500 sq ft.
California State Law requires that dwelling units can only be used as short-term rentals or Airbnbs for terms of 30 days or longer.
Per the Costa-Hawkins Act of 1995, Signal Hill does not impose rent control on dwellings constructed after February 1, 1995. This means most new-build ADUs are exempt. However, if the primary dwelling unit is subject to rent control, it might apply to the ADU as well.
While encouraging the use of electric appliances for efficiency and sustainability, Signal Hill does not prohibit gas appliances in new ADUs as long as all relevant installation and safety standards are met. Signal Hill property owners must also conduct methane testing and submit methane mitigation plans for their ADU.
In Signal Hill you are only required to install sprinklers in a new ADU if the primary dwelling unit has them as well. You may also be required to install them if the ADU is located within a special fire hazard zone.
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