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What are the requirements to build ADU in Unincorporated San Diego County?
Adding an ADU in San Diego County offers a valuable opportunity to expand your living space and provide affordable housing for adult children transitioning to independent living. To ensure a successful ADU project, it is crucial to understand the local regulations affecting your property and assess the financial viability of building an ADU in San Diego County. This guide offers a thorough summary of San Diego County's ADU requirements and key financial considerations to help you plan and complete your project effectively.
ADU regulations for properties with a single-family home
How many ADUs can you build in San Diego County?
In San Diego County, you can build one ADU on your property if it has an existing or proposed single-family dwelling in a residential or mixed-use zone, regardless of whether they are attached or detached from the primary building.
How large can an attached ADU be in Unincorporated San Diego County?
The floor area of an attached ADU can be up to 50% of the floor area of the single-family dwelling, with a maximum size of 1,200 square feet. For ADUs with more than one bedroom, the size can range from 850 to 1,000 square feet, regardless of the existing unit's size.
How large can a detached ADU be in Unincorporated San Diego County?
The total floor area of a detached ADU cannot be larger than 1,200 square feet, regardless of the square footage of the existing single-family dwelling.
Can I build a 2-story ADU in Unincorporated San Diego County?
Yes, it's possible to build a two-story ADU in the County, as long as it complies with the local zoning regulations. As it can reach a maximum height of 25 feet, it satisfies the criteria for a two-story structure.
Is there a minimum size for an ADU?
No, the County has not established any rules regarding the minimum size of an ADU. However, to create livable spaces, the Building Code will require a minimum size for each room type.
Can I convert the existing space to an ADU?
Yes, properties zoned for residential use with an existing or proposed single-family dwelling are eligible for converting one allowed and existing accessory structure into an ADU.
What is the maximum height for an ADU?
The maximum height for an attached ADU on a property with a single-family house is 12 feet. However, if the proposed accessory structure, when attached to the ADU, surpasses 1,000 sq. ft. in total area or 12 feet in height, it needs to follow the main building setbacks and height regulations specified in the Zoning Ordinance.
Additionally, a detached ADU cannot be higher than 25 feet.
ADU regulations for properties with a multi-family building
How many ADUs does San Diego County allow for multifamily properties?
San Diego County allows multiple ADUs within an existing or proposed multifamily unit located in a residential or mixed-use zone. Portions of the complex that are not used as livable space can be converted into ADUs, with a limit of up to 25% of the existing multifamily dwelling units. Additionally, up to two detached ADUs are allowed per lot.
How large can an attached ADU for a multifamily building be in Unincorporated San Diego County?
For multifamily properties, the attached ADU can be a maximum of 1,200 square feet. If the ADU has more than one bedroom, its size can vary from 850 to 1,000 square feet, regardless of the size of the existing unit.
How large can a detached ADU for a multifamily building be in Unincorporated San Diego County?
The total floor area of a detached ADU cannot be larger than 1,200 square feet, regardless of the square footage of the existing multifamily dwelling.
Can you stack detached ADUs on top of each other?
Currently, Unincorporated San Diego County has not specified regulations concerning the stacking of detached ADUs on top of each other.
Can you attach two ADUs to each other?
No, attaching two ADUs to each other is not allowed.
Can you convert the existing space to an ADU?
Yes, within a multifamily property, only structures or rooms that are not currently used as living space can potentially be converted into an ADU.
What is the maximum height for an ADU on a property with a multi-family building
Unincorporated San Diego County did not specify the height limit for multifamily properties.
What ADU types are allowed to build in Unincorporated San Diego County?
Unincorporated San Diego County permits the construction of various ADU types, including:
(A) Detached ADU: A stand-alone structure built separately from the main dwelling.
(B) Attached ADU: A newly built addition physically connected to the primary home.
(C) Converted ADU: A renovated non-livable space—such as a garage, shed, or storage area—turned into a functional living unit with a kitchen or kitchenette and a bathroom.
Repurposing existing structures into ADUs provides more design flexibility, as setback and height regulations are usually not a concern. These structures can also be expanded for additional space, though renovating older buildings may reveal unexpected issues that could raise costs.
ADU setbacks from the property lines and other buildings
What are the required setbacks for an ADU in San Diego County?
For an ADU built above a detached accessory structure, a minimum distance of 4 feet is required from the side and rear property lines. On corner lots, the exterior side yard should also be set back at least 4 feet from the edge of the easement, street, or property boundary.
What is the minimum distance the ADU must be from existing structures?
There is no specified minimum distance for ADUs from existing structures in San Diego County, but most cities require a distance of at least 6 feet.
Are setbacks required when converting existing structures into ADU?
No, setbacks are not required if an existing and allowed accessory structure or a portion of it is being converted into an ADU, except for fire safety considerations.
Can I build an ADU in the front yard of my house in Unincorporated San Diego County?
Yes, but only if there’s no other feasible spot on the property for an ADU of at least 800 square feet. Make sure to comply with the zoning setback requirements.
Design requirements for ADU
How many bedrooms can an ADU have?
ADUs in San Diego County should have at least one bedroom, as opposed to studio units.
Does an ADU need to have a kitchen?
Yes, an ADU in the county requires a full kitchen, not just an efficiency kitchen unlike for JADUs.
Does an ADU require independent utility meters?
No, a separate electric meter is not allowed. However, the county’s planning department advised that if you have questions about separate utility connections, services, or metering requirements, contact your local utility provider for guidance following state regulations.
What is the minimum ceiling height?
Although not explicitly stated in local regulations, the California Building Code requires habitable spaces in new residential developments, including ADUs, to have a minimum ceiling height of 7 feet.
Find out the maximum ADU size for your property here
The parking requirements for ADU
What is the parking requirement for an ADU in Unincorporated San Diego County?
In Unincorporated San Diego County, an ADU is required to have one parking space. However, there are exemptions to this requirement. If the ADU is within a half-mile radius of public transit or located within an architecturally and historically significant historic district, it does not need to provide a parking space.
Where can I have a parking space on my property?
Parking for an ADU may be located within the setbacks or in an existing driveway, often arranged as tandem parking. Additionally, there is no requirement to replace parking spaces if a garage, carport, or covered parking structure is demolished as part of ADU construction or converted into an ADU.
How to get permits for your ADU
How long does it take to get an ADU permit in Unincorporated San Diego County?
In Unincorporated San Diego County, obtaining an ADU permit typically takes 6 months to a year, with initial plan checks averaging about one month. However, processing times may extend due to multiple review cycles. Plan checks for ADU projects in Unincorporated San Diego County are estimated to cost $430.
Does Unincorporated San Diego County require in-person submission of plans for an ADU?
Yes. As of now, the County of San Diego is required to submit the ADU plans in person. They're not accepting applications through the website at this time.
Does Unincorporated San Diego County require coastal development permits?
Yes, if your property falls within the coastal zone, Unincorporated San Diego County requires coastal development permits. These permits are obtained through the county's Local Coastal Program (LCP), which simplifies the approval process by bypassing the need for California Coastal Commission approval.
When do you need a licensed professional to design an ADU in Unincorporated San Diego County?
In Unincorporated San Diego County, whether a licensed professional is needed for ADU design depends on the project's complexity.
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How much does it cost to build an ADU in Unincorporated San Diego County?
In Unincorporated San Diego County, the expense to construct an ADU is approximately $325 per square foot. Additionally, you need to factor in extra costs like permits, architect fees, and engineering expenses. For example, the total cost for a 900-square-foot ADU would be around $330,000, including both hard and soft costs.
Is it profitable to build an ADU in Unincorporated San Diego County?
The profitability of constructing an ADU in Unincorporated San Diego County relies on construction costs and the local real estate market. A 900-square-foot ADU in the county has an estimated market value of roughly $510,000. Considering a total project cost of around $330,000, this results in an approximate return on investment of 55%.
You can also assess profitability based on potential rental income or the advantages of having family members reside on the same property.
Can you sell an ADU in Unincorporated San Diego County?
California's AB 1033 permits local authorities to set rules for selling ADUs and primary homes as condominiums, as long as they comply with existing development regulations.
In Unincorporated San Diego County, local laws dictate the sale of ADUs. You can sell an ADU if it was built by a recognized nonprofit organization if there is a legitimate tenancy-in-common agreement, or if the city approves selling the ADU and the primary home as separate condominiums.
Are ADUs rent-controlled in Unincorporated San Diego County?
No. ADUs in Unincorporated San Diego County are not subject to rent control regulations. This regulation specifically affects buildings that are at least 15 years old. Since they're considered new construction, laws like AB 1482, which involves rent control, do not apply.
How do I get money to build an ADU in Unincorporated San Diego County?
In Unincorporated San Diego County, homeowners can secure funding for ADU construction through the California Housing Finance Agency (CalHFA). The ADU Grant Program offers grants of up to $40,000 to eligible homeowners, providing financial support without the need for repayment. This program aims to facilitate ADU construction as part of a broader statewide effort to promote affordable housing solutions.
Find out how much value an ADU could add to your property.
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