ADU rules in South El Monte

Can I add an ADU to my property?

An ADU is a second home with its own kitchen and bathroom. In South El Monte, it can be a separate backyard building, an addition to your house, or a conversion of existing space.

ADUs are allowed on qualifying residential properties with an existing or proposed home. Some mixed-use properties qualify too. Duplexes and apartment buildings have their own options for adding units.

For a property inside South El Monte, the City handles ADU planning and building permits. Los Angeles County’s ADU program covers a different permitting area; its plans and rules do not automatically apply to your address.

How big can my ADU be?

An addition attached to an existing house is generally also limited to half the house’s floor area. However, that limit and certain yard and lot-coverage rules cannot reduce the allowed ADU below 800 square feet.

Can it be two stories?

An attached ADU may be up to two stories, with a height limit of 25 feet or the property’s zoning limit, whichever is lower. Separate ADUs covered by the City’s local design rules are limited to one story.

Near qualifying major transit stops or high-quality transit corridors, a separate ADU may reach 18 feet, with up to 2 extra feet for a roof that matches the main home’s roof pitch. The height allowance for transit is more specific than the parking exception for a nearby bus stop.

Can I convert my garage?

Yes. An existing garage can be converted into an ADU if it can meet the building and fire-safety requirements for living space. It needs its own outside entrance, kitchen, and bathroom.

You do not have to replace parking spaces lost when a garage or carport is converted or removed for an ADU. A conversion may also be able to keep its existing distance from the property lines, subject to fire safety. That can make it possible to reuse a garage closer than 4 feet to a boundary.

Will I need another parking space?

When parking is required, the City generally asks for one off-street space. It can be on the driveway, including behind another parked car. Common exceptions include:

• The ADU is within a half-mile walk of public transit.
• The ADU is within the main house or another existing building.
• The property is in a qualifying historic district.
• Street parking permits are required but are not available to the ADU resident.
• An established car-share stop is within one block.

ADUs that qualify for California’s separate exemption from local development standards also have parking protections.

South El Monte requirements to plan for

Some ADUs must meet additional City design rules. These can affect the floor plan, windows, and exterior before you submit drawings.

These rules do not apply to every ADU

Certain ADUs qualify for California protections that exempt them from these extra local design rules. Examples include qualifying conversions and a qualifying detached ADU of up to 800 square feet. Meeting the size alone is not enough; placement and other conditions still matter.

For ADUs subject to the City’s local rules, South El Monte also calls for 50% open space on the lot. That requirement cannot prevent an otherwise qualifying 800-square-foot ADU. Your designer and the City Planning Department can identify which requirements apply to your drawings.

California ADU guide · South El Monte ADU rules

Are pre-approved plans available?

Pre-approved plans are ready-made ADU designs that a city has already reviewed. They can save design time, though you still need a permit and drawings showing how the ADU fits your property.

Call the South El Monte City Planning Department at 626-579-6540 ext. 3040 to ask about available pre-approved ADU plans.

How do I get a permit?

1. Contact the City Planning Department.Share your address and what you want to build. City staff can help you understand the requirements for your property.
2. Prepare and submit your plans.Your designer or contractor can help prepare the drawings. Submit them through the City’s online permit system.
3. Complete the City review.The City may request changes to the drawings before issuing a permit.
4. Build and schedule inspections.Once the permit is issued, construction can begin. The City inspects the work at several stages.

Visit the City permit page

How long does City review take?

The City has 15 business days to tell you whether your application is complete or what is missing. Once it has a complete application, the usual deadline for a decision is 60 days.

If you are applying for a new main house at the same time, the ADU decision can wait for that application. A delay you request can also pause the clock. These review periods do not include preparing drawings or building the ADU.

An ADU that meets the applicable requirements is reviewed without a public hearing.

What fees and utility work should I expect?

Plan-review and permit charges can apply even to a small ADU. The City’s permit page links to its fee information.

• 750 square feet or less: the ADU is exempt from impact fees, which help fund public facilities. This does not remove every permit, school, or utility charge.
• More than 750 square feet: any impact fee must be proportional to the ADU’s size compared with the main home.
• Water and sewer: qualifying conversions can avoid a new separate connection and its connection charges. New detached units may need separate service. Other utility providers set their own connection requirements.

Will I need fire sprinklers?

The ADU needs sprinklers if the main home is required to have them. Adding an ADU does not, by itself, require you to install sprinklers in the existing main home.

City permits and fee information

Can I rent out my ADU?

Yes. South El Monte allows ADUs to be rented, but not as short-term vacation rentals. The City’s minimum rental term is 30 days; some state-exempt ADUs require terms longer than 30 days.

For a regular ADU, you do not have to live in the main house or the ADU. Junior ADUs can have different owner-residency rules, explained below.

What could rental income look like?

Use rents for similar-sized homes in South El Monte when estimating income. Bedroom count, parking, laundry, and utilities included in the rent can all affect the comparison.

Try the ADU Rental Calculator

Common questions