ADU rules in Newport Beach

Newport Beach permits a detached ADU on any lot in a residential or mixed-use zone (R-A, R-1, R-BI, R-2, RM and RMD, the mixed-use districts and residential planned communities) that has an existing or proposed home, through a ministerial building permit (NBMC 20.48.200(C); Table 2-1). The code allows one detached new-construction ADU on a single-unit lot and up to two on a lot with an existing or proposed multi-unit building, but its 'Unless precluded by Government Code Section 66323' preface lets the state counts control, and the city's January 2026 summary already allows up to eight detached ADUs beside an existing multi-unit building (never more than its existing units). Detached units may be 16 ft tall (18 ft within one-half mile of a major transit stop or beside a multistory multi-unit building, plus 2 ft for a matching roof pitch) with 4 ft side and rear setbacks, and an ADU over a detached garage may reach two stories within the zone height limit. Inside the coastal zone the same unit is allowed under Title 21 (Table 21.18-1) but also needs a coastal development permit, and the coastal text still limits a lot to one ADU category.

One attached new-construction ADU is allowed on a lot with a single-unit or multi-unit home, plus one internal ADU converted from existing or proposed space (or from an existing accessory structure with up to 150 sq ft added for access), and on multi-unit lots conversions of non-livable space up to 25 percent of the existing units, at least one (NBMC 20.48.200(D)(1), (2), (4)). A junior ADU of up to 500 sq ft may be created within or attached to a single-unit home in addition to an ADU, but not on a multi-unit lot (20.48.200(E)). Attached ADUs and JADUs follow the base zone height limit, which the city's Exhibit B findings for Ord. 2025-20 say exceeds the 25 ft state floor in its residential zones. In the coastal zone § 21.48.200(E) still says only one ADU category may be used per lot and Table 21.18-2 allows 'one accessory dwelling unit' per single-unit lot, rules HCD's 2024 findings called contrary to the 'any combination' language of Gov. Code 66323(a); the pending coastal amendment PA2025-0093 would adopt the Title 20 wording.

NBMC 20.48.200(F)(4)(a) caps a new detached or attached ADU at 850 sq ft for a studio or one-bedroom unit and 1,000 sq ft for two or more bedrooms, the same figures as the coastal § 21.48.200(G)(4)(a); conversions of existing or proposed space are not size-capped, and a JADU may be 500 sq ft. Floor area limits, site coverage, open space and front setbacks can shrink an ADU but never below 800 sq ft where no other alternative complies ((F)(4)(c)); the city's January 2026 summary applies that guarantee to existing development only, so an ADU built together with a new house must fit the lot's floor area limit. The 2025 text exempts units built under the state-exempt pathway (Gov. Code 66323) from local standards, which matters for detached ADUs beside multi-unit buildings that 66323(a)(4) leaves without a size cap. Below-grade basement ADUs are excluded from the floor area limit ((F)(5)). The caps equal the Gov. Code 66321(b)(2) floor, but the code does not say they are measured as interior livable space as the statute does.

No owner has to live on a property with an ADU: the owner-occupancy clause in NBMC 20.48.200(H)(3) covers only junior ADUs, and Gov. Code 66315 bars owner-occupancy conditions on ADUs. For a JADU the codified text still requires an owner with title to live in the main home or the JADU and a recorded deed restriction saying so ((H)(3), (I)), but since 1-1-2026 Gov. Code 66333(b) (as amended by AB 1154) allows that requirement only where the JADU shares sanitation facilities with the house, so a JADU with its own bathroom carries no owner-occupancy duty. Inside the coastal zone § 21.48.200(J)(1) still requires a recorded deed restriction for ADUs as well as JADUs that recites the 'owner-occupancy requirements'; HCD's 10-1-2024 findings (item 13) say ADU deed restrictions are not authorized, and the pending coastal amendment PA2025-0093 limits the restriction to JADUs.

Outside the coastal zone NBMC 20.48.200(F)(8) requires at most one space per ADU (tandem or on an existing driveway is fine, but not in the front setback unless the driveway is 20 ft deep, nor in a rear setback on an alley) and none for a JADU. No space is required for an ADU inside an existing or proposed home or accessory structure, within one-half mile walking distance of public transit (defined to include any fixed-route bus stop), in a historic district, where on-street permits are not offered to the occupant, within one block of a car-share vehicle, or built together with a new home, and parking removed or converted for an ADU (or a garage converted for a JADU) need not be replaced. Inside the coastal zone § 21.48.200(G)(8) drops the new-home exemption and requires replacement parking (in any configuration, including tandem spaces or lifts) when a garage, carport or covered parking is demolished or converted for an ADU; that rule conflicts with Gov. Code 66314(d)(11) but stands as certified LCP text under the Coastal Act savings clause of 66329(a), and the city's January 2026 summary applies it. A flat one-space rule also reaches studios, while 66314(d)(10)(A) caps parking at one space per unit or per bedroom, whichever is less.

ADUs and JADUs are approved ministerially through building permit plan check, 'without discretionary review or a hearing', within 60 days of a complete application (NBMC 20.48.200(C)(3)). Inside the coastal zone a coastal development permit under Chapter 21.52 is also required unless the project is exempt or categorically excluded, but no public hearing is held: the notice states that none will be held and invites written comments (§ 21.48.200(D)(1)-(2)), and Gov. Code 66329(a) requires a decision within 60 days, concurrent with the building permit. § 21.48.200(D)(3) still routes appealable ADU permits straight to the Coastal Commission, although 66329(c), in force since 10-10-2025 (AB 462), makes local ADU coastal permit decisions unappealable under Public Resources Code 30603. Coastal resource overlays (Bluff, Canyon, scenic and habitat protection) also apply ((C)(3)), and a project that also needs a variance goes to a Planning Commission hearing, as two 2026 coastal permits for new homes with an ADU or JADU and setback variances did (PC2026-014, PC2026-021).

Both codes say an ADU or JADU 'shall not be rented for periods of thirty (30) days or less' (NBMC 20.48.200(H)(2), 21.48.200(I)(2)), which matches the longer-than-30-days term Gov. Code 66323(e) and 66333(g) require for state-exempt units and JADUs and is one day stricter than the 30-days-or-longer term 66315 allows for ordinary ADUs. The short term lodging chapter adds that an ADU 'shall not be considered a lodging unit' (5.95.010), so no ADU can hold one of the city's capped short term lodging permits (1,475 residential and 75 multi-use, 1,550 in all, with no new permits on R-1 parcels since 2004). Ord. 2026-14 (adopted 9-8-2026, effective about 10-8-2026) changes only reinstatement and waiting-list procedure. ADUs and JADUs may be rented but not sold separately except as Gov. Code 66341 allows (20.48.200(H)(1)); the coastal text omits that exception, and the city has not opted into 66342 ADU condominiums.