ADU rules in Pasadena

Detached ADUs are a permitted use in every RS and RM district and in the commercial, public-semipublic and specific-plan mixed-use zones that allow housing, on any lot with a proposed or existing dwelling. A single-family lot may combine one new-construction ADU (detached or attached), one conversion ADU and one junior ADU, and an 800 sq ft new-construction Exemption ADU with 4 ft side and rear setbacks is always available. A lot with an existing multifamily building may add up to eight detached ADUs (never more than its existing unit count), and a lot with a proposed multifamily building two. On Hillside Overlay lots served by streets 26 ft wide or narrower only the 800 sq ft exemption unit or a conversion is allowed, and lots created by an SB 9 urban lot split that use the two-unit provisions get no new ADU.

Attached new-construction ADUs (additions, including second-story units up to 25 ft and two stories) and conversions of existing space in the house, a garage or another accessory structure are permitted on the same terms as detached units, and a junior ADU of up to 500 sq ft may be created inside the single-family house or attached garage. On multifamily sites, ADUs can be converted from non-livable space such as storage rooms, attics, basements and garages: at least one, and up to 25 percent of the existing units. A conversion may add up to 150 sq ft for ingress and egress, an attached conversion needs its own exterior entrance, and on single-family sites a new attached non-exemption ADU's entrance and exterior stairs must not be visible from the street unless that would prevent the unit.

On single-family sites a new detached ADU may reach 1,200 sq ft and a new attached ADU 850 sq ft (studio or one bedroom) or 1,000 sq ft (more than one bedroom). New units of 800 sq ft or less with 4 ft side and rear setbacks are Exemption ADUs, which skip the zone's lot coverage, floor area and encroachment-plane limits and may sit in the front yard, and conversions of existing space have no size cap; units over 800 sq ft must meet the underlying zone's standards, the front-yard setback and a 6 ft building separation. In Hillside Overlay districts (except HD-1, Upper Hastings Ranch) detached units cap at 1,000 sq ft, and on lots served by streets with 26 ft or less of pavement (about 1,600 lots) new construction is limited to 800 sq ft. Detached units may be 18 ft and two stories (16 ft in hillside overlays, in landmark or historic districts where visible from the street, and for exemption units in the front-yard setback, rising to 18 ft near major transit or beside multistory buildings, plus 2 ft to match roof pitch near transit); attached units 25 ft or the zone limit; multifamily-site exemption ADUs have no size cap.

Pasadena imposes no owner-occupancy requirement on ADUs, at application or afterward, consistent with Gov. Code 66315, which bars one. Owner occupancy applies only to a junior ADU that shares sanitation facilities with the house: then either the house or the JADU must be owner-occupied (not required where the owner is a government agency, land trust or housing organization), and the owner must record a city covenant before the building permit issues. A JADU with its own bathroom carries no occupancy rule, which matches the current state rule in Gov. Code 66333(b).

The code requires one space (covered, uncovered or tandem on the existing driveway) for an ADU on a single-family site, but waives it for Exemption ADUs, sites within a half-mile walk of a public transit stop (any fixed-route bus stop counts under Gov. Code 66313(m)), units within existing or proposed space, landmark and historic districts, lots within one block of a car-share location, and ADUs filed with a new house that meet another exemption. ADUs on multifamily sites need no parking, and a garage, carport or space demolished or converted for an ADU or JADU need not be replaced. In practice the space reaches only a new unit over 800 sq ft on a single-family lot away from transit, mostly in the hillside areas the city's own findings describe as thinly served; on a plain reading of Gov. Code 66314(d)(10)(A) (one space per unit or per bedroom, whichever is less) a studio owes none.

ADU and JADU applications are ministerial: the Planning Director approves, conditionally approves or denies them within the Gov. Code 66317, 66320 and 66335 time limits (15 business days for completeness, 60 days to decide, no hearing), and plans go through the city's online CSS permit portal and plan check. Two older chapters lack an ADU carve-out: the Hillside Development Permit rule lists any new dwelling or structure in the HD and HD-SR overlays (17.29.030.A.2), and 17.62.090.A requires a Certificate of Appropriateness for new construction in landmark and historic districts. Gov. Code 66317(a)(1) and (c) keep ADUs out of discretionary review, so only objective standards such as the not-visible-from-the-street rule apply.

Any rental of an ADU or JADU legally created on or after January 1, 2017 must be for a term longer than 30 days, and 17.50.296.E.2.c bars ADUs and accessory structures permitted after that date from the short-term rental program; an older permitted ADU may be short-term rented only as part of the host's primary residence under an annual STR permit (host in residence nine months a year, 90 un-hosted nights a year, TOT and TBID). Rented ADUs and JADUs are Rental Units under Charter Article XVIII (Measure H): they must be registered every year (September 1 to October 31; $236.54 per unit for FY 2026-27) and carry just-cause eviction protection, while rent caps reach only units built before February 1, 1995. ADUs may not be sold separately except through a qualified nonprofit under Gov. Code 66341; Pasadena has not opted into 66342 ADU condominiums.