ADU regulations for properties with a single-family home

How many ADUs can you build in Los Angeles County?

In Los Angeles County, one ADU is allowed for each legally built single-family residence, whether the ADU is attached or detached from the primary building.

How large can an attached ADU be in Unincorporated Los Angeles County?

The total floor area of the attached ADU cannot be larger than 50 percent of the habitable area of the single-family residence or 1,200 square feet, whichever is less. However, a minimum of an 800-square-foot ADU is allowed.

How large can a detached ADU be in Unincorporated Los Angeles County?

The total floor area for a detached ADU has a maximum size of 1,200 square feet.

Can I build a 2-story ADU in Unincorporated Los Angeles County?

Yes, you can build a two-story ADU in Unincorporated Los Angeles County. Local zoning regulations allow ADUs to reach heights of up to 25 feet, making a two-story design feasible.

Is there a minimum size for an ADU?

Yes, ADUs are required to have a minimum floor area of 150 square feet, with at least one habitable room covering at least 70 square feet.

Can I convert the existing space to an ADU?

Yes, you can convert existing space within a single-family residence including legally built accessory structures, into an ADU and expand the floor area by up to 150 square feet in Los Angeles County.

What is the maximum height for an ADU?

The maximum height for an ADU on a property with a single-family house, whether existing or proposed, is 25 feet.

ADU regulations for properties with a multi-family building

How many ADUs does Unincorporated Los Angeles County allow for multifamily properties?

In Unincorporated Los Angeles County, multifamily properties can have at least one ADU within the existing building and can convert up to 25% of the existing multifamily units. Also, a maximum of two detached ADUs is allowed on the property.

How large can an attached ADU for a multifamily building be in Unincorporated Los Angeles County?

The size of an attached ADU for a multifamily building is restricted. It cannot surpass 50 percent of the habitable area of the single-family residence or 1,200 square feet, whichever is smaller. However, typically, a minimum of an 800-square-foot ADU is allowed.

How large can a detached ADU for a multifamily building be in Unincorporated Los Angeles County?

In Unincorporated Los Angeles County, there is no maximum size specified for a detached ADU in a multifamily building.

Can I stack detached ADUs on top of each other?

As of now, Unincorporated Los Angeles County does not have rules overseeing the stacking of detached ADUs.

Can I attach two ADUs to each other?

Yes, it is allowed to attach two detached ADUs to each other in multi-family residences.

Can I convert the existing space to an ADU?

Yes, within a multifamily property, you can convert existing space to an ADU, including legally built accessory structures, with the option to expand the floor area by up to 150 square feet.

What is the maximum height for an ADU on a property with a multi-family building

For properties located within a half-mile radius of a major transit stop or high-quality transit corridor, there are specific height limitations for ADUs on properties with multifamily buildings. In such cases, a detached ADU, which is an accessory to either a one-story or multi-story multifamily residence, can have a maximum height of 18 feet.

However, if the ADU is aligned with the roof pitch of the primary dwelling, an additional 2 feet may be allowed, bringing the maximum height to 20 feet.

What ADU types are allowed to build in Unincorporated Los Angeles County?

In Unincorporated Los Angeles County, various types of ADUs are permitted, including:

(A) Detached ADU: A standalone structure built separately from the main dwelling.

(B) Attached ADU: A new addition physically connected to the primary house.

(C) Converted ADU: A repurposed non-livable area—such as a garage, shed, or storage space—transformed into a livable unit with a kitchen or kitchenette and a bathroom.

Repurposing existing buildings into ADUs offers more design flexibility since setback and height limitations are generally not a concern. These structures can also be expanded for additional space, though renovating older buildings may reveal hidden issues that could increase costs.

ADU setbacks from the property lines and other buildings

What are the required setbacks for an ADU in Unincorporated Los Angeles County?

An ADU requires side and rear yard setbacks of at least 4 feet. However, the county does not specify regulations for corner or through lots.

What is the minimum distance the ADU must have from the existing structures?

The ADU should be at least 6 feet away from existing structures.

Are setbacks required when converting existing structures into ADU?

No setbacks are needed when converting existing structures into ADUs, as long as they use the same footprint and dimensions.

Can I build an ADU in the front yard of my house in Unincorporated Los Angeles County?

Yes, only if there is no place on the property to build a min. 800 sqft ADU. You just need to follow the zoning setbacks.

Design requirements for ADU

How many bedrooms can an ADU have?

Unincorporated Los Angeles County does not specify a maximum number of bedrooms for an ADU. However, given the maximum allowable size of 1,200 square feet, it can accommodate at least one bedroom.

Does an ADU need to have a kitchen?

Yes, an ADU is typically equipped with a full kitchen, as opposed to JADUs, which may have an efficiency kitchen.

Does an ADU require independent utility meters?

No, it's not required to separate utility meters for an ADU, but owners can choose to request separate meters if they prefer.

What is the minimum ceiling height?

While not explicitly specified in the local code, the California Building Code requires a minimum ceiling height of 7 feet for habitable spaces in new residential developments, including ADUs.

Find out the maximum ADU size for your property here

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The parking requirements for ADU

What is the parking requirement for an ADU in Unincorporated Los Angeles County?

In Unincorporated Los Angeles County, parking requirements for an ADU are:

• Spaces should be 8.5 ft. x 18 ft. Compact spaces are not allowed.
• Existing parking rules for single-family and multifamily homes apply if the parking structure is not converted into an ADU.
• A 26-foot-clear vehicle backup space is needed.

For ADUs in Very High Fire Hazard Severity Zones, one uncovered parking space is required unless the ADU meets any of these exemptions:

• No bedroom.
• Detached, max 800 sq. ft. floor area, and max 16 ft. height.
• Detached, max 16 ft. height, and 4 ft. rear and side yard setbacks.
• Entirely within existing primary residence or legal accessory structure with no expansion.
• Within ½ mile of public transit.
• In a historic district.
• On-street parking permits are required but not available for the ADU occupant.
• Car share vehicles within one block.

Where can I have a parking space on my property?

When parking is required for an ADU or residential building, it can be located on a driveway or in an area previously used as a driveway to a garage or carport that has been demolished or converted into an ADU. If a garage, carport, or covered parking structure is demolished or converted into an ADU, no replacement parking is required for the ADU or the residential building.

How to get permits for your ADU

How long does it take to get an ADU permit in Unincorporated Los Angeles County?

Permits should be acquired from the Planning and Building Department before construction can begin. The community development director typically approves ADU permit applications within 16 weeks of receiving all required documentation. Plan checks for ADU projects in Unincorporated Los Angeles County are estimated to cost $35.28.

Does Unincorporated Los Angeles County require in-person submission of plans for an ADU?

No, Unincorporated Los Angeles County allows plans for an ADU to be submitted online or in person. Online submissions provide email updates, while in-person submissions require payment of the plan check invoice at the Building and Safety Division office.

Does Unincorporated Los Angeles County require coastal development permits?

Yes, in Unincorporated Los Angeles County, any construction or changes made within the Coastal Zone require a Coastal Development Permit (CDP). This permit is usually issued by either the Coastal Commission or the local government if they have an approved Local Coastal Program (LCP).

When do you need a licensed professional to design an ADU in Unincorporated Los Angeles County?

In Unincorporated Los Angeles County, whether a licensed professional is needed for ADU design depends on the project's level of complexity.

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How much does it cost to build an ADU in Unincorporated Los Angeles County?

In Unincorporated Los Angeles County, constructing an ADU costs around $380 per square foot. It's also important to include additional expenses such as permits, architect fees, and engineering costs. For instance, the total cost for a 900-square-foot ADU would be approximately $380,000, covering both hard and soft costs.

Is it profitable to build an ADU in Unincorporated Los Angeles County?

The profitability of an ADU in Unincorporated Los Angeles County depends on the construction costs and the local real estate market. A 900-square-foot ADU in the county has an estimated market value of about $1,300,000. With a total project cost of around $380,000, this yields a return on investment of roughly 250%.

Profitability can also be evaluated based on potential rental income or the benefits of having family members living on the same property.

Can you sell an ADU in Unincorporated Los Angeles County?

Under California's AB 1033, local governments can create regulations for the sale of accessory dwelling units (ADUs) and primary homes as condominiums, provided they follow existing ADU development guidelines.

In Unincorporated Los Angeles County, the sale of ADUs is subject to local regulations. An ADU can be sold if it was constructed by a recognized nonprofit organization, if there is a recorded tenancy-in-common agreement, or if the city allows for the separate sale of the ADU and the primary residence as distinct condominiums.

Are ADUs rent-controlled in Unincorporated Los Angeles County?

No, ADUs in Unincorporated Los Angeles County are not subject to rent control regulations. These regulations typically apply to buildings that are at least 15 years old, but ADUs, being new constructions, are not covered by laws like AB 1482, which involve rent control.

How do I get money to build an ADU in Unincorporated Los Angeles County?

You can apply for the CalHFA ADU Grant Program, which provides grants of up to $40,000 for pre-development costs like permits and site preparation. Eligibility is based on low- or moderate-income status, allowing household incomes up to $158,000 for owner-occupied properties in LA County. Homeowners can also select their tenants for the ADU.

Find out how much value an ADU could add to your property.

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