Building an ADU in Redondo Beach. Rules, costs, timeline.

Can I build an ADU in Redondo Beach?

Five things to know before you start

If you read nothing else on this page, read these. They are the five points that change the most Redondo Beach projects.

How many units a lot allows

Read on its own, RBMC § 10-2.1506 looks like a two-unit ceiling. The streamlined track at subsection (b)(4) covers one ADU plus one junior ADU on a single-family lot, and the standard track at subsection (c) is limited to one ADU per lot. State law is wider than both.

• An ADU carved out of existing space. Inside the house or an accessory building, with up to 150 extra square feet for ingress and egress, and no separate square-foot cap.
• A junior ADU. Up to 500 square feet, entirely within the single-family home (Gov. Code § 66313(d)).
• A new detached ADU. Up to 800 square feet, with 4-foot side and rear setbacks and 16 feet of height or more where Gov. Code § 66321 allows it.

Multifamily lots

RBMC § 10-2.1506(b)(5) allows conversion of non-livable space — storage, boiler rooms, passageways, attics, basements, garages — into ADUs equal to 25 percent of the existing units, with a minimum of one. It then allows two detached ADUs per lot. That last figure is where state law goes further: Gov. Code § 66323(a)(4)(A)(ii), as raised by SB 1211 effective 1 January 2025, requires up to eight detached ADUs on a lot with an existing multifamily building, capped at the number of existing units. A proposed multifamily building gets up to two. Junior ADUs are a single-family product only.

Owner-occupancy

This is the single most consequential thing on the page, so it is worth stating flatly. RBMC § 10-2.1506(a)(10) provides that for any ADU permitted after 1 January 2025 in a single-family residential zone, the primary unit or an ADU shall be occupied by the owner. The coastal parallel goes further and asks for a recorded covenant before the building permit issues. The City’s own ADU resource page still lists the requirement.

Gov. Code § 66315 does not allow it. A local agency may not require an owner to occupy the property as a condition of an ADU; the only occupancy term a city may impose is a rental term longer than 30 days. The local sentence tracks an allowance in the former Gov. Code § 65852.2(a)(6) that did not carry over when SB 477 renumbered ADU law in 2024. Junior ADUs are the exception, and a narrow one: under Gov. Code § 66333(b), as amended by AB 1154 effective 1 January 2026, owner-occupancy reaches a junior ADU only where it shares sanitation facilities with the house.

What an ADU costs in Redondo Beach (2026)

Plan pricing does not vary by neighborhood or by whether the lot is coastal. The fee covers architectural design, structural engineering, Title 24 energy compliance, and every piece of permit processing and plan check correspondence through to an issued permit. Once the plans are permitted you arrange construction — build it yourself, bring your own licensed contractor, or build with one of our vetted partners.

The build estimate covers labor and materials, interior finishes, cabinetry, countertops, flooring, fixtures, appliances and utility connections. What sits outside it: City permit and plan check fees, any coastal permit fee where one applies, and site-specific work such as grading on the sloped blocks above the Esplanade, retaining walls, long utility runs or drainage. We identify and price all of that in the proposal before you commit.

City fees

Building permit and plan check fees in Redondo Beach are set by the City Council through the Master Fee Schedule and are assessed at the building permit stage. They are not a flat ADU rate, so they scale with what you build. We pass them through at cost. The City does not publish a single clean ADU figure, so we would rather link the schedule than invent a number.

Impact fees are the part state law controls, and the local ordinance agrees with it. RBMC § 10-2.1506(c)(10) charges no impact fees on an ADU under 750 square feet and charges proportionally above it. Gov. Code § 66311.5(c)(1) makes that mandatory: an ADU with 750 square feet of interior livable space or less is exempt outright, and above that, fees must be charged in proportion to the size of the ADU relative to the primary dwelling. A unit under 500 square feet is also outside school impact fees (§ 66311.5(c)(3)).

What it returns

Long-term tenancy is the only option here, so the return is a rent roll rather than nightly income. For a government benchmark, HUD publishes Fair Market Rents for the Los Angeles–Long Beach–Glendale metro area. The FY2026 figures as revised, effective 21 May 2026, are $2,079 for a studio, $2,328 for a one-bedroom, $2,903 for a two-bedroom and $3,681 for a three-bedroom.

Read those as a floor rather than a forecast. They cover the whole metro across all housing stock and ages, including units decades older than anything you would build. A new, well-finished detached ADU typically rents above them, and a beach-adjacent South Bay address with the El Segundo employment corridor a short drive north supports that. Run your own numbers on our ADU ROI calculator.

When an ADU isn’t the right move

A guide that never says “not you” is a brochure. Four situations where an ADU here is the wrong call, or the wrong call right now.

• Your plan depends on nightly rental income. The 30-day minimum is not a technicality and it is not waivable. If short-term rental is the business case, there is no version of this that works in Redondo Beach.
• You are counting on selling the unit separately. No local AB 1033 opt-in has been adopted here, so an ADU cannot be sold as a condominium. If your exit depends on that, you are planning around a policy change that may not come.
• You wanted a two-story detached unit. The detached envelope is about 20 feet at its most generous. A stacked, small-footprint detached plan is not available as a stock design; it needs a modification or a custom design.
• You need it finished in under six months. Design through move-in runs roughly six to nine months on a Signature plan and longer on a custom one. A family situation that needs housing sooner is better served another way.

The rules that make Redondo Beach different

Two rulebooks, one of them out of date

Most cities have a single ADU section. Redondo Beach has two. RBMC § 10-2.1506 sits in the zoning code and was last amended by Ord. 3264 c.s., effective 8 December 2023. RBMC § 10-5.1506 sits in the Coastal Land Use Plan Implementing Ordinance and was last amended in October 2022. Which one applies depends on whether your parcel is inside the Coastal Zone.

That four-year gap matters, because state ADU law changed three times inside it. The coastal section predates SB 1211, AB 1154 and AB 462 entirely, and it still cites the former Gov. Code § 65852.2 rather than the renumbered §§ 66310–66342. It is not a trap so much as a lag: where the coastal text falls below a state floor, Gov. Code § 66316 makes the state floor the operative rule.

Which lots are coastal

The Coastal Zone boundary is a mapped line, not a neighborhood, and it does not follow street names in a way you can reason about from an address. The only reliable answer is a parcel check against the City’s certified Local Coastal Program map, which we run before we quote a schedule. One line the code itself draws is worth knowing: an ADU Parking Overlay applies west of Catalina Avenue, where a parking space is expected unless a Gov. Code § 66322 exemption removes it.

There is one more piece of good news buried in the City’s own guidance. Redondo Beach says it uses Categorical Exclusion Orders where they apply, to exempt ADUs in heavily urbanized infill areas from coastal development permit requirements entirely, where there is no risk to coastal resources. That is worth asking about directly, because it can remove a whole permit from the schedule.

What the Coastal Act still protects

AB 462 streamlined the process; it did not suspend the Coastal Act. Setbacks and design rules that exist to protect sensitive habitat, public view corridors, or to reduce coastal flooding and erosion risk are not waivable, and the City says as much. The flexibility it offers is on the non-coastal design standards, through variances and modifications. Plan the site work around the resource constraints and the rest of the process is now genuinely fast.

Rental term and separate sale

An ADU or junior ADU here may not be rented for less than 30 days. State law backs the floor rather than fighting it: Gov. Code § 66323(e) requires a term longer than 30 days for a § 66323 unit, and § 66333(g) does the same for a junior ADU. Expect the restriction to be recorded.

On separate sale, RBMC § 10-2.1506(b)(1)(b) bars conveying an ADU apart from the primary dwelling except under the AB 1033 framework, now codified at Gov. Code § 66342. No local AB 1033 condominium opt-in has been adopted in Redondo Beach. Santa Monica and Culver City have opted in; this city has not, and until it does the prohibition stands.

Legalizing an older unit

If there is an unpermitted unit on your lot built before 1 January 2020, there is a route. Gov. Code § 66311.7, added by AB 2533, provides a streamlined legalization path and stops a city denying the permit over building-code issues alone unless they implicate health and safety. Redondo Beach publishes its own AB 2533 page through Building and Safety, which is the right place to start.