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Guide

ADU Types in Los Angeles.

Plain-English information about the kinds of accessory dwelling units a Los Angeles County homeowner can consider.

Photo: Backyard Cottage by Sightline Institute, CC BY 2.0, via Openverse (flickr).

Last reviewed 2 min read

An accessory dwelling unit can be a separate small home, an addition to your house, a converted garage, or a junior ADU built inside your existing home. This section compares the main types.

What this topic covers

The four common types are detached, attached, conversion and JADU. A garage conversion is a way of building an ADU or a JADU. Getting the vocabulary right helps you read your city's rules.

Key facts

  • Detached: a local ordinance may cap size, but not below 850 square feet (studio or 1 bedroom) or 1,000 square feet (2+ bedrooms), per ABAG's July 2025 summary. 1,200 square feet applies only where a city has no ADU ordinance.
  • Attached: the same 850/1,000 square foot floor applies. The 50 percent of the main home figure applies only where a city has no ADU ordinance.
  • Conversions under section 66323(a)(1) have no size limit, and an existing structure converted in the same location needs no setback.
  • Section 66313(d) defines a JADU as "no more than 500 square feet in size and contained entirely within a single-family residence," and section 66333 requires the owner to live on the property.
  • HCD told the City of Los Angeles that one converted ADU, one new detached ADU and one JADU can be combined, totaling three units.

Guides in this hub

Questions to ask before you pick

  • Do I have a garage or other structure worth converting, and is it in sound shape?
  • Is the yard big enough for a detached unit after setbacks?
  • Do I plan to live on the property? A JADU requires it.
  • Is the lot in a fire, flood or hillside area that adds requirements?

What does not change by type

Review time is 60 days for a complete application (section 66317). An ADU generally cannot be sold apart from the main home. There are no impact fees for ADUs of 750 square feet or less. Many local rules limit rentals to more than 30 days, so check your agency.

Which types are allowed on your lot depends on local rules.

Guides in this section.