ADU Size Standards

An accessory dwelling unit (ADU) is a great way to leverage available space on your property to increase its value, maximize the housing options for your family and generate a passive income.

ADUs can be either attached or detached from the primary dwelling or created through the conversion of an existing garage or an interior space in a single-family or multi-family residential lot.

Whichever type of ADU you chose to build, it should conform to all applicable zoning and building codes regarding minimum lot size, floor area, setbacks, or height requirements in order to be permitted for construction.

This article contains everything you need to know about ADU size standards in the greater Los Angeles area as per California’s 2020 Housing Laws (AB 2299). The new laws aimed at easing the way for the construction of secondary units to address the shortage of affordable urban housing in the state.

Reach out to us at (323) 405-8909 for any questions at any stage of your ADU building process and our ADU consultants will get back to you with the most accurate and comprehensive information.

Is an ADU Subject to Lot Size Requirements?

There is no longer a minimum lot size requirement for a new ADU as long as a permitted single or multi-family dwelling exists on the property.

How Big is an ADU?

The maximum size of an ADU can be 1,200 sqft in California. An ADU must have a minimum living area of 150 sqft.

What is the Maximum Size for ADU in Los Angeles?

The maximum size of an ADU in the City of Los Angeles is 1200 sqft. The living room or bedroom in the secondary dwelling could not be less than 70 sqft.

Attached ADU Size Standards in Los Angeles

The floor area of an attached dwelling should be up to 1200 sqft or 50 percent of the primary dwelling, whichever is smaller.

For instance, if the size of your home is 1,200 sqft, the maximum size of a unit is attached to the primary dwelling can be 600 sqft.

Any habitable room in a unit attached to the primary dwelling, except kitchens, can have a minimum horizontal dimension of seven feet in any direction.

Detached ADU Size Standards in Los Angeles

The maximum floor size of a detached dwelling cannot exceed 1,200 sqft, irrespective of the size of the main structure.

A new stand-alone unit that is less than 800 sqft in size is subject to automatic approval.

What is the size of a JADU?

A Junior ADU or JADU, no matter converted from an existing lot in the house or another structure can have a minimum size of 150 and a maximum size of 500 sqft and should be contained within a single-family lot.

The size of a habitable room in a junior dwelling unit, except for the kitchen, cannot be less than 70 sqft.

Expansion: A Junior ADU can be expanded up to 150 sqft beyond the footprint of its existing structure. This expansion, however, is strictly limited to the purposes of accommodating the ingress/egress of the dwelling, including (walkways, driveway, etc.).

junior adu
junior adu 3

Does ADU Square Footage Count?

Yes. All ADUs adds livable square footage to your property.

For example, a 1,200 sqft stand-alone unit adds 1,200 sqft of new livable space to your house.

Since the appraisers take into account the livable square footage when determining how much a house is worth, stand-alone units are typically the most valuable among all types of ADUs.

It has been shown that detached units have the potential to increase the resale value of a house by 30-40 percent.

Need Help Navigating Your Local ADU Regulations?

For more than a decade, we at Construction Consulting Services Inc have been helping the homeowners in Los Angeles just like you, navigate the local zoning rules and regulations for their dream ADUs and streamline their approvals.

Talk to an expert with experience in ADU construction to find out the estimates involved when putting up an ADU. Now, let us review the different types of ADU mentioned earlier on.

Addition to your current house structureATTACHED ADU »
Add separated independent ADUDETACHED UNIT »
Convert the garage to an ADUGARAGE CONVERSION »
Convert any space of the main house, or add a new floorINTERIOR CONVERSION »
Add more than one ADUMULTI TENANT ADU »
Maximize the square footageJUNIOR ADU »