ADU rules in Mission Viejo

Detached ADUs are allowed in every residential zone with only a building permit: MVMC Sec. 9.10.020(b)(12) says an ADU and a JADU 'subject only to a building permit are allowed in any residential zone,' and the Sec. 9.10.015 use table lists accessory dwelling units as P (permitted) in all six RPD zones (RPD 3.5, 6.5, 14, 30, 50 and 80). The codified text still confines a detached ADU to the rear half of the parcel (item b) and caps a single-story detached unit at 20 feet (item c); the city's March 2026 ADU Reference Guide drops the rear-half rule, lets a two-story detached ADU fit within the same 20 feet, and uses 4-foot side and rear setbacks. On multifamily lots the guide follows Gov. Code 66323(a)(4): up to eight detached ADUs with an existing building (never more than its unit count) and up to two with a proposed one.

Attached additions and internal conversions of existing space, including garages and detached accessory buildings, are allowed with a building permit in every RPD zone under Sec. 9.10.020(b)(12) and the Sec. 9.10.015 use table. Codified item d caps a two-story attached ADU at 35 feet and item e requires an independent exterior entrance on a side or rear facade not facing the same street as the main home; the city guide says attached ADUs follow the base-zone height, may be two stories, and may connect internally through a 1-hour fire-rated door. A JADU of up to 500 sq ft inside a single-family home (an attached garage counts) may sit beside an ADU, and conversions of non-habitable space in existing multifamily buildings are allowed for at least one unit and up to 25 percent of the existing units.

The codified subsection sets no size cap of its own: Sec. 9.10.020(b)(12) has ADUs 'processed and permitted pursuant to' the state ADU statute, so the state limits apply: an attached ADU may not exceed 50 percent of the existing home and a detached ADU 1,200 sq ft (Gov. Code 66314(d)(4)-(5)), and no limit may block an 800 sq ft unit with 4-foot side and rear setbacks (66321(b)(3); item a says the 60 percent single-family lot coverage cannot preclude it). The city's ADU Reference Guide (editions of 10-9-2024 and 3-24-2026) prints 'Studio/One-Bedroom = 850, Greater than One Bedroom = 1,200' for new attached and detached units, measures the 50 percent attached cap including the garage, and leaves internal conversions uncapped; the 850 figure sits at the 66321(b)(2) floor but has no ordinance behind it, and the city's permit log shows one-bedroom attached ADUs of 885, 890 and 1,200 sq ft approved in 2025. JADUs are limited to 500 sq ft (66313(d)); detached ADUs are held to 20 feet and attached ADUs to the base-zone height (35 feet for two stories in the code).

No owner occupancy for ADUs. Codified Sec. 9.10.020(b)(12)(l) keeps the owner-occupancy rule only for ADUs permitted before 1-1-2020 (whatever applied when permitted) and exempts ADUs permitted from 1-1-2020 through 12-31-2024; it is silent on later permits, and Gov. Code 66315 bars any owner-occupancy condition on an ADU. Item m still requires the owner to live in the main home or the JADU for every JADU, and the March 2026 guide repeats that and has the owner record a JADU deed restriction; since 1-1-2026 Gov. Code 66333(b) allows owner occupancy only where the JADU shares sanitation with the house, so a JADU with its own bathroom carries no owner-occupancy requirement despite the local text. Pending Ord. 26-363 rewrites the JADU covenant to the shared-sanitation rule.

The code sets no ADU parking number: the Sec. 9.25.020 parking table says only 'See section 9.10.020(12),' and that subsection's lone parking rule (item h) demands replacement parking when a JADU is created in an attached garage. The city guide requires one space per new attached or detached ADU, waived within one-half mile walking distance of transit, in a historic district, where on-street permits are required but not offered, or within one block of a car-share location, and none for internal conversions, multifamily conversions or JADUs; converted garages and carports need no replacement parking, JADU garage conversions included, contrary to item h. State limits: at most one space per unit or per bedroom, whichever is less (Gov. Code 66314(d)(10)(A), which a one-space rule exceeds for studios), the six 66322(a) exemptions (the guide omits (a)(6), an ADU applied for with a new home), no replacement parking (66314(d)(11)), no JADU parking (66334(a)) and none for the 800 sq ft state-exempt unit (66323(b)).

Ministerial. Sec. 9.10.020(b)(12) allows an ADU and a JADU 'subject only to a building permit' in any residential zone, the use table marks ADUs P in every RPD zone, and the city guide says ministerial review of all ADUs and JADUs happens in building permit plan check (the city also offers a pre-approved 800 sq ft one-bedroom detached plan). Gov. Code 66317 requires a completeness decision within 15 business days and approval or denial within 60 days, without discretionary review or a hearing. The code's subjective 'architecturally compatible' clause (item g) and the general Chapter 9.43 architectural review process (HOA committee and neighbor sign-off, a Planning and Transportation Commission hearing on any disapproval) would conflict with the objective-standards rule of 66314(b)(1) and with 66317 if applied to ADUs; nothing in the city's ADU materials applies Chapter 9.43, and Ord. 26-363 strikes item g.

Codified Sec. 9.10.020(b)(12)(k) requires a covenant, recorded before the building permit, stating the ADU or JADU may be rented as an independent dwelling 'but not for a term that is shorter than 30 days' and may not be sold apart from the main home and parcel; the March 2026 guide says short-term lodging is prohibited for every ADU and JADU but now records the deed restriction for JADUs only. The 30-day floor is lawful for ordinary ADUs under Gov. Code 66315, but state-exempt units (66323(e)) and JADUs (66333(g)) must be rented for longer than 30 days. Short-term rental of a main home is not banned citywide: Chapter 3.25 (Ord. 24-352, 1-23-2024) treats short-term rental units as hotels for the 8 percent transient occupancy tax, with registration through the city's Deckard portal. Separate sale is barred except through the qualified-nonprofit path of 66341, and the city has no 66342 condominium opt-in. Pending Ord. 26-363 replaces item k with an explicit ADU ban on terms under 30 days, a separate-sale and lot-split ban, and a JADU-only covenant.