Building an ADU in Lomita. Rules, costs, timeline.

What you can build: size, height, and setbacks

Everything in this section comes from Ordinance No. 854 as the City presents it in the ADU Development Chart, with state-law citations called out where the statute preempts or supplements the local rule. We won’t re-cite the ordinance on every line; assume it under each subsection unless we say otherwise.

Size limits

A new detached ADU may reach 850 square feet as a studio or one-bedroom, or 1,000 square feet with two or more bedrooms — the exact minimums state law requires a city to allow (Gov. Code § 66321(b)(2)). One pairing rule to plan around: when the lot carries both a detached ADU and a JADU, the detached unit is capped at 800 square feet — the same envelope as the § 66323 by-right detached path. A new attached ADU carries the same 850/1,000 caps plus a second limit of 50 percent of the main house’s living area, whichever is less. State law puts a hard bottom under that percentage: it cannot restrict an attached ADU below the 850/1,000 floors, so on a smaller house the 50-percent prong gives way (Gov. Code § 66321(b)(2); HCD ADU Handbook, pp. 38–39). A JADU is capped at 500 square feet (Gov. Code § 66313(d)), and the smallest ADU the City will permit is 150 square feet — an efficiency unit.

Conversions get more room. A garage, an accessory structure, or interior space of the house converted to an ADU carries no maximum floor area at all — the unit is whatever the existing space measures. A garage or other accessory structure may also expand up to 150 square feet beyond its footprint, solely for entry and exit (Gov. Code § 66323(a)(1)(A)).

Setbacks

Side and rear setbacks for new construction are 4 feet — the state-law floor in Gov. Code § 66314(d)(7), and a city may not require more for a conforming ADU. The front setback is 20 feet, or 10 feet on the secondary frontage of a corner lot. Conversions within an existing footprint carry no setback requirement, and 4 feet applies only to the portion expanded for entry and exit. Keep 6 feet between the ADU and other structures on the lot, and don’t plan the unit into a recorded easement — the ordinance requires the easement holder’s written permission before an ADU encroaches on one.

Maximum height

The standard envelope is 16 feet for a new detached ADU built with the reduced 4-foot setbacks — the state-law floor in Gov. Code § 66321(b)(4)(A) — rising to 18 feet plus 2 more feet to match the main house’s roof pitch within a half mile of a major transit stop (Gov. Code § 66321(b)(4)(B)). An attached ADU may reach 25 feet, matching Gov. Code § 66321(b)(4)(D). Lomita then adds a conditional path most cities don’t offer — the 27-foot envelope tied to the Pacific Coast Highway line, covered in its own section below.

What that means for design: on the standard 4-foot-setback path, Lomita is a single-story detached-ADU market, and our six single-story plans are all designed to sit at or under 16 feet. Our three two-story Signature Homes are detached-only products that need roughly a 25-foot envelope — they only pencil here on a lot north of PCH that can hold the zone’s full setbacks. If your lot is deep enough for that trade, it’s worth checking; for most yards, the single-story lineup is the straighter path.

Parking

The baseline is one off-street space per ADU. The exemptions in Gov. Code § 66322(a) apply on top — among them transit proximity, a historic district, an ADU created within an existing primary or accessory structure, an on-street permit district where the ADU occupant isn’t offered a permit, and car-share proximity.

Two rules cut in your favor regardless of that list. Converting or demolishing a garage, carport, or covered space for the ADU never triggers replacement parking (Gov. Code § 66314(d)(11)). And a JADU requires no parking at all: the City’s chart carves out the converted garage portion, but that text states older law — Gov. Code § 66334(a) now bars JADU parking requirements in every case, garage conversion included.

Lot coverage, open space, and design standards

One local standard is specific to larger units: an ADU over 800 square feet must keep 225 square feet of continuous private recreation area on the lot, with a minimum interior dimension of 10 feet. Underneath it sits the state guarantee: no lot-coverage, open-space, or minimum-lot-size math may block one 800-square-foot ADU at 16 feet with 4-foot setbacks (Gov. Code § 66321(b)(3)) — so the recreation-area rule shapes the over-800 plans, not the by-right envelope.

Design standards are objective and short: architecture, roof pitch, materials, and colors match the primary dwelling; the ADU gets its own main entrance, which may not open directly onto an alley; a garage-door opening replaced for a conversion gets a finished facade with a window or entry; an entry light and visible address numerals are required; and plans on treed lots carry a mature-tree protection plan.

Owner-occupancy

Owner-occupancy is not required for an ADU. The City’s chart still describes a requirement “waived until January 1, 2025” — language written before the Legislature made the ban permanent. State law now forbids an owner-occupancy requirement for any ADU on your lot, with no sunset (Gov. Code § 66315). You can build the unit and rent it whether or not you live on the property.

JADUs are different, and the rule just changed. AB 1154 amended Gov. Code § 66333(b) effective January 1, 2026: JADU owner-occupancy may only be required where the JADU shares sanitation facilities with the primary dwelling. A JADU with its own bathroom falls outside the rule entirely. Lomita’s chart states the older, broader JADU owner-occupancy rule — the shared-bathroom narrowing preempts it.

Impact fees and the deed restriction

An ADU of 750 square feet or less pays no development impact fees statewide (Gov. Code § 66311.5(c)(1)), and the City’s chart repeats the exemption. Above 750 square feet, impact fees apply per Council resolution — and state law requires them to be proportional to the primary dwelling’s size, never a flat per-unit charge. Every ADU takes a recorded deed restriction with two covenants: no sale separate from the primary residence (with the narrow nonprofit carve-out in Gov. Code § 66341), and no rental shorter than 30 days.

Permitting timeline

A conforming ADU is approved ministerially — building permits only, no discretionary review, no hearing, no neighbor sign-off (Gov. Code § 66317). The City must act on a complete application within 60 days or the project is deemed approved. One post-permit step is unique to Lomita: the owner notifies adjacent residential parcels 30 business days before construction begins. It is a courtesy notice, not an approval step — nobody gets a veto.

How California state law overrides Lomita

Ordinance No. 854 took effect in July 2023, and the Legislature has amended ADU law every year since. Where the local text and the current statute disagree, the statute controls (Gov. Code § 66316). Three gaps matter to real projects.

• Units per single-family lot. The City’s chart says one ADU plus one JADU. Gov. Code § 66323 requires more: a conversion ADU from existing space, a JADU up to 500 square feet, and a new-construction detached ADU up to 800 square feet may be combined on the same lot — the stack the HCD ADU Handbook lays out at page 17. The Handbook at page 18 reads the statute to require at least one § 66314 ordinance ADU on top of that stack. The narrower local count is preempted.
• ADU owner-occupancy. The chart describes an owner-occupancy requirement “waived until January 1, 2025” — implying it snaps back. It doesn’t: state law bars ADU owner-occupancy requirements outright for any ADU on your lot, with no sunset (Gov. Code § 66315), and AB 1154 narrowed the JADU version to shared-sanitation units effective January 1, 2026 (Gov. Code § 66333(b)).
• JADU parking. The chart requires no JADU parking “unless the garage portion is converted.” That carve-out states pre-2025 law. Gov. Code § 66334(a) now forbids requiring parking for a JADU in every case, including a garage-conversion JADU.

Two more state floors sit quietly underneath the ordinance. On a multifamily lot, the SB 1211 counts apply as written: conversion ADUs in non-livable space up to 25 percent of the existing unit count, and up to eight detached ADUs on a lot with an existing multifamily dwelling, capped at the number of existing units (Gov. Code § 66323(a)(3)–(4)) — the chart’s two-detached figure is a floor from an earlier statute, not a ceiling. And an unpermitted unit built before January 1, 2020 has a streamlined legalization pathway under AB 2533 (Gov. Code § 66311.7, renumbered from § 66332 by 2025 legislation).

Renting out your new ADU

Long-term rental only. The deed restriction Ordinance No. 854 requires bars any rental shorter than 30 days — the strictest limit state law lets a city impose (Gov. Code §§ 66323(e), 66333(g)). Month-to-month and annual leases are untouched; short-stay platforms are off the table. If short-term income was the plan, this is the rule that changes it.

For a rent benchmark, the government figure is HUD’s Fair Market Rent for the Los Angeles-Long Beach-Glendale HUD Metro FMR Area, which covers Lomita. For FY2026, effective October 1, 2025, FMR is $1,863 for a one-bedroom, $2,085 for a two-bedroom, and $2,601 for a three-bedroom. Those are metro-wide figures spanning the full range of housing stock and unit ages, so treat them as a floor rather than a forecast — a newly built detached ADU in a South Bay neighborhood a short drive from the beach cities and the Palos Verdes Peninsula typically rents above FMR, and we’d rather point you at a verifiable number than an invented one. A local property manager can price your specific street.

Two structural points in this city’s favor. There is no owner-occupancy requirement for an ADU, so the unit can be rented whether or not you live on site. And the tenant pool is steady — the South Bay medical corridor anchored by the hospitals in neighboring Torrance, the aerospace employers spread across the South Bay, and renters priced out of the beach cities and the Hill who want the same commute for less.