La Mirada ADU rules

Maximum size

A new ADU with more than one bedroom may be up to 1,200 sq ft. The code sets 800 sq ft for a new ADU with one bedroom or less, but state law (Gov. Code § 66321(b)(2)) does not let a city set a cap below 850 sq ft for a studio or one bedroom. A converted ADU may be as large as the existing permitted structure (an accessory structure may add 150 sq ft for entry and exit). The home and ADU together must meet the zone's lot coverage and floor area limits, but those limits, open space, front setbacks and minimum lot size cannot block an 800 sq ft ADU.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(c)(2)(A)(i)(d), (c)(12), (c)(14), accessed 2026-11-03.

Setbacks

New ADUs need at least 4 ft from rear and interior side lot lines and must meet the zone's front and street-side setbacks, unless that would block an 800 sq ft ADU. An ADU at the front of a lot must keep as much of the front setback as it can. New ADUs need 10 ft clear between buildings on the lot, wall to wall. No added setback is needed to convert existing space or rebuild in the same place and size, beyond what fire and safety rules require.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(c)(3), accessed 2026-11-03.

Local ADU rules

La Mirada's ADU rules are in Municipal Code § 21.18.060, added by Ordinance 736 (Zoning Amendment No. 57), adopted January 14, 2025. That ordinance deleted the old ADU chapter (Chapter 21.54). The online code (2024 edition) still shows the old chapter, so this summary uses the adopted ordinance text. ADUs and JADUs get a ministerial site plan review and zoning clearance, with no hearing or public notice.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(b)-(c); Ord. 736 § 5, accessed 2026-11-03.

ADU types

ADUs are allowed in the R-1, R-3, R-4, Planned Unit Development, Mixed Use Overlay and Special Housing Overlay zones. On a single-family lot: one ADU inside the existing or proposed home or an existing accessory structure, one new detached ADU, and one JADU. On a lot with existing multifamily homes: ADUs converted from non-livable space (at least one, up to 25% of the units) and up to eight detached ADUs with 4 ft side and rear setbacks, not more than the number of homes on the lot. No ADU or JADU is allowed on a lot that used both the urban lot split and two-unit rules.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(c)(1)-(2), accessed 2026-11-03.

Height

An ADU may be up to two stories and 25 ft to the top of the roof, with an interior loft where the building code allows. A second-story ADU, including one over a garage, must stay within the roof line below it and may extend over the main home by no more than 20%. Exterior stairs to an ADU over a garage need 5 ft side and rear setbacks and may not run along the front.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(c)(7)-(8), accessed 2026-11-03.

Parking

One paved off-street space per ADU, in addition to the main home's parking. It may be tandem, covered or uncovered, and may be on a driveway widened to 30 ft, but not in the front setback except on a paved driveway. No space is needed within one mile walking distance of a major transit stop, in a historic district, for an ADU fully inside the home, or within one block of a car share vehicle. Garage or carport parking converted or replaced by an ADU does not have to be replaced, but the driveway must still hold at least one car. JADUs need no parking.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(c)(11), (c)(15), accessed 2026-11-03.

Junior ADUs

One JADU of up to 500 sq ft (including any addition) is allowed inside an existing or proposed single-family home or an existing accessory structure, with up to 150 sq ft added to an accessory structure for entry. It needs exterior access and a kitchen, and may share a bathroom with the home. Before the building permit, the owner records a City-form declaration that the JADU will not be sold separately and will be rented only for terms over 30 days. No parking is needed.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(c)(2)(A)(iii), (c)(14)(D), (c)(15), (c)(22), accessed 2026-11-03.

Site and design standards

An ADU needs a permanent foundation, its own whole-number address, a paved path from the street to its entrance, and a decorative porch at its main entrance. Bedrooms must open off a hall or common area. Outdoor equipment must be screened, kept on the ground, at least 3 ft from side and rear lines, and out of the front yard. Each home needs at least 100 sq ft of private open space (6 ft each way), one 15-gallon tree is planted with each new ADU or JADU where the site allows, and trees removed are replaced three for one. The City's objective multifamily design standards (§ 21.18.080) also apply. State law (Gov. Code § 66323) lets every homeowner build certain ADUs, such as a detached ADU up to 800 sq ft with 4 ft side and rear setbacks, without added local standards.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(c)(5)-(6), (c)(9), (c)(13)(A)-(B), (c)(17)-(18), (e), accessed 2026-11-03.

Utilities, sprinklers and renting

The owner may give the ADU or JADU separate utility connections or connect it to the main home's systems. Fire sprinklers are needed only if the main home needs them. ADUs and JADUs may not be rented for less than 30 days. No owner occupancy is required for ADUs. An ADU may be sold separately only if deed restricted for low- or moderate-income households for at least 45 years or bought by a qualified nonprofit.

Source: City of La Mirada Ordinance No. 736, Attachment B, § 21.18.060 Accessory Dwelling Units (ADU) (City Council agenda, January 14, 2025), § 21.18.060(c)(16), (c)(19)-(21)(A), (d), accessed 2026-11-03.

Planning contact

La Mirada's Planning Division reviews ADU applications. Phone: (562) 943-0131.

Source: City of La Mirada, Planning Division, Planning Division page, accessed 2026-11-03.