Building an ADU in Rolling Hills Estates. Rules, costs, timeline.

Can I build an ADU in Rolling Hills Estates?

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 Rolling Hills Estates projects.

Number of units per lot — what the state stack really allows

Everything in this section is grounded in RHEMC § 17.56.050 and Gov. Code § 66323; we won’t re-cite the local section on every line. The local text allows one internal or attached ADU plus one JADU per single-family parcel, or one detached ADU (new construction, or a conversion of a detached structure like a garage) combined only with a JADU. Read alone, that caps you at one ADU.

State law is more generous, and the ordinance concedes the point: RHEMC § 17.56.090 exempts any application that qualifies under Gov. Code § 66323(a)(1)–(4) from local standards inconsistent with that section. Under § 66323(a)(1)–(2) — confirmed by the HCD ADU Handbook (March 2026), p. 17 — a single-family lot may combine a conversion ADU (carved from existing space of the home or an accessory structure), a JADU (up to 500 sqft inside the home), and a new detached ADU of up to 800 sqft with 4-foot setbacks. That is up to two ADUs plus a JADU — the number this page uses.

On multifamily parcels in the Mixed Use Overlay District, the restated ordinance already matches SB 1211: internal conversion ADUs in non-livable space up to 25% of existing units, total ADUs up to the number of existing units, and up to eight detached ADUs on an existing multifamily lot (two with a proposed one) (RHEMC § 17.56.050(B); Gov. Code § 66323(a)(3)–(4)).

Owner-occupancy

You do not have to live on the property to build or rent an ADU. Ordinance No. 752 removed the former requirement — which HCD had flagged and Gov. Code § 66315 prohibits — so an investment or family-flex build works here the same way it does anywhere else in the county. The JADU is the one exception, and a narrower one than the local text suggests: RHEMC § 17.56.110(E) still requires the owner to occupy the home or the JADU and to certify it annually, but AB 1154 (effective January 1, 2026) amended Gov. Code § 66333 so owner-occupancy reaches only a JADU that shares sanitation facilities with the primary home. Give the JADU its own bathroom and the state rule — not the broader local one — controls.

What an ADU costs in Rolling Hills Estates (2026)

Our Signature plans are fixed-price — architectural design and full permit processing included, the same number whether the lot is on the peninsula, in the South Bay flats, or in the Valley. Construction is separate: once your plans are permitted, you build it yourself, bring your own licensed contractor, or build with one of our vetted construction partners. The figures below are the estimated cost to build each model with an independent licensed general contractor:

In Rolling Hills Estates the two-story models and the 1,080–1,200 sqft plans are shown for reference — the detached envelope here is single story and 1,000 sqft, so the Lincoln is the ceiling as drawn. Custom work is priced per project, $9,990–$19,990 for design and permit processing.

City fees and pass-throughs

ADUs and JADUs pay the City’s standard permit and inspection fees, which are adopted under RHEMC § 3.04.060 and scale with project valuation, and ADUs are subject to applicable public facility fees under RHEMC Chapter 17.74 (§ 17.56.130). The City’s ADU Program page includes a fee calculator — run your project through it before you budget. Two state-law protections do real work here: an ADU of 750 sqft or less pays no development impact fees (Gov. Code § 66311.5(c)(1)), and utility connection fees or capacity charges must be proportionate to the ADU — its square footage or fixture count, not a new-home rate (RHEMC § 17.56.060(N)). An internal ADU within the existing home needs no separate utility connection at all unless it is built with a new house.

What it returns: renting your ADU

Long-term rental only — RHEMC § 17.56.100 sets a 30-consecutive-day minimum term, and state law itself mandates that rentals of § 66323 units run longer than 30 days (Gov. Code § 66323(e); § 66333(g) for JADUs). 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 Rolling Hills Estates. For FY 2026, as revised effective May 21, 2026: $2,079 for a studio, $2,328 for a one-bedroom, $2,903 for a two-bedroom, and $3,681 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 inside the Palos Verdes Peninsula Unified School District typically rents well above FMR — we would rather point you at a verifiable number than an invented one. A local property manager can price your specific street.

HUD FMR figures: FY 2026 Fair Market Rents, Los Angeles–Long Beach–Glendale HUD Metro FMR Area, as revised effective May 21, 2026 (huduser.gov; Federal Register, Apr. 21, 2026). Your specific ADU’s performance depends on finish level, lot, access, and the rental market at the time you lease it. For payback math keyed to your lot, use the ADU ROI calculator or the ADU calculator.

When an ADU isn’t the right move

Not every Rolling Hills Estates property is a good ADU candidate, and it is cheaper to learn that now than after you have paid for plans. Four situations where we would tell you to wait, choose a different unit type, or not build:

• Your numbers depend on short-term rental income. They will not work. The 30-day minimum in RHEMC § 17.56.100 has no ADU carve-out. Run the math on a 30+ day tenancy or reconsider.
• You want a separate-sale exit. The City has not opted into AB 1033, so the ADU cannot be sold apart from the house. If a condo-style exit is the plan, this is the wrong jurisdiction for it.
• You need two stories of detached space, exactly as our stock plans draw it. The detached envelope is 16 feet. The honest routes are a single-story plan, an attached two-story design, or a custom unit — not a variance, which takes the project out of ministerial review entirely.
• Your septic system is already at capacity. On an OWTS parcel, added bedrooms mean county wastewater review — and if the system needs replacement, that cost can rival the ADU foundation. Get the septic evaluation first; some lots are better served by a JADU that shares the home’s plumbing.

The rules that make Rolling Hills Estates different

An equestrian city, by design

Rolling Hills Estates incorporated in 1957 to protect its rural, horse-keeping character, and the ADU chapter carries that DNA. Three siting rules do the work (RHEMC § 17.56.060(F), (I)–(J)): the ADU shares the primary home’s driveway unless the lot fronts a public alley or a permitted corner-lot secondary access; no vehicular access from a bridle trail, ever; and on H District lots the Chapter 17.36 horsekeeping provisions — corrals, stables, access to the trail network — are maintained where possible. The balance tips in the homeowner’s favor when they conflict: the ordinance says horsekeeping standards may not preclude an ADU or unreasonably restrict one. In practice, the design question on an equestrian lot is placement — keeping the corral, the turnout, and the new unit from fighting over the same corner of the lot.

The HCD story: from 15 findings to a rewrite

On March 19, 2025, HCD issued a findings letter under Gov. Code § 66326 concluding the City’s prior ADU ordinance (Ord. 745, 2023) did not comply with state law — fifteen findings, including an ADU owner-occupancy requirement, subjective “neighborhood compatibility” design review, and unit counts below the § 66323 floor. The City’s answer was Ordinance No. 752, adopted August 26, 2025, which replaced Chapter 17.56 in its entirety. The rewrite dropped ADU owner-occupancy, moved design review to published objective standards, codified the SB 1211 multifamily counts, allowed JADUs in attached garages, and added a savings clause (§ 17.56.090) that defers to Gov. Code § 66323 wherever the local standards would conflict. HCD followed up with a Letter of Technical Assistance on December 5, 2025; where any residual local language is still narrower than state law, state law controls (Gov. Code § 66316).

Why this matters to you: the rulebook here is newer — and closer to state law — than in most LA County cities, but the internet has not caught up. Summaries written against the 2020 or 2023 ordinances describe rules that no longer exist. Check the date on anything you read, including city handouts.

Fire, septic, and hillside overlays

Parts of the peninsula carry elevated fire-hazard designations, and the City’s ADU submittal materials route those lots through Los Angeles County Fire’s Fuel Modification Unit and a Cal Water fire-flow test; the ADU itself never needs fire sprinklers unless the primary home does (RHEMC § 17.56.060(E); Gov. Code § 66314(d)(12)). Parcels on onsite wastewater treatment systems add a county septic review sized to the new bedrooms. Neither overlay is a reason not to build — both are reasons to sequence the paperwork early, which is exactly what the timeline section above budgets for.

Historic properties

On a designated or potential historic resource under the Landmark Overlay Zones chapter, an attached-ADU addition must be inset or separated by a connector offset at least 18 inches from the parallel side or rear wall, so the new work reads as distinct from the historic structure (RHEMC § 17.56.060(O)). It is a detailing rule, not a barrier — and conversions inside existing space avoid it entirely.

No separate-sale path

The restated chapter contains no AB 1033 condominium opt-in, so a Rolling Hills Estates ADU cannot be sold separately from the primary home (Gov. Code § 66342). Among LA-area cities only a handful have opted in — Santa Monica (SMMC § 9.31.026, 2025) and Culver City (CCMC § 17.400.096, 2026) among them. Build here for rental income, family housing, or long-term value, not for a condo exit.