Pasadena, California | ADUs and SB 9

Pasadena, California ADUs and SB 9: Sizes, Heights, Parking and Two-Unit Developments

On a house lot in Pasadena, California, the two main ways to add homes are accessory dwelling units (ADUs) under Section 17.50.275 of the Zoning Code and SB 9 projects, which Pasadena calls Two-Unit Developments, under Section 17.22.050.G. Both are approved by staff against fixed rules, without a public hearing. This page gives the sizes, heights, setbacks and parking for each, the changes made in 2026, and where the City's text and state law differ. The state rules behind them are on the ADU law page and the SB 9 page.

The Current ADU Text

Section 17.50.275 on Municode carries the history note "Ord. No. 7464, § 11, 1-26-2026," so it already includes the January 2026 rewrite. Two later changes are worth knowing. Ordinance No. 7471, adopted June 22, 2026, amends Section 17.50.275 again; Municode lists it but had not printed its text on October 9, 2026. The staff summary for the June 15, 2026 Council meeting describes the ADU change as a clarification that the rule against new second-story windows along side and rear lot lines applies to "all non-exemption ADUs when the proposed setback is less than five feet," and "shall not apply to Junior Accessory Dwelling Units." The Supplement 79 text prints that window rule under the junior ADU standards.

The City's Accessory Dwelling Units page is older than both. It says the "Updated regulations for Accessory Dwelling Units (ADUs) and Junior ADUs went into effect on May 20,2024," and points to Ordinance No. 7420. Where the web page and the code differ, the code controls. Section 17.50.275.A.1 adds one more rule for every case: "In the event of a conflict between this section and applicable state law, state law shall prevail."

The Planning Director or a designee reviews ADU permits as ministerial permits, which means staff check the plans against fixed standards and may not use judgment about design. The code ties the review time to Government Code Sections 66317, 66320 and 66335.

How Many ADUs, and How Big

ADUs are permitted "in all zoning districts that permit single-family or multifamily dwelling residential uses on sites with at least one proposed or existing dwelling." On a lot with a house, the owner may add one new construction ADU, attached or detached, one conversion ADU made from existing space, and one junior ADU.

Pasadena sorts ADUs into two groups. An Exemption ADU is one the state says every city must allow: a new ADU of up to 800 square feet with side and rear setbacks of four feet, or a conversion of existing space that may grow by "not more than 150 square feet" for entry and exit. Exemption ADUs skip the zone's own standards. Every other ADU is a non-exemption ADU, and it must meet "all applicable development standards of the underlying zone (e.g., encroachment plane, floor area, lot coverage limits, setbacks, etc.)" that apply to the house.

Source: Pasadena Municipal Code, Sec. 17.50.275.B, D and E, Supplement 79.

Every ADU must be at least 150 square feet. Floor area may be measured by the Zoning Code method or the California Building Code method, "whichever method is preferred by the applicant." A newly built non-exemption ADU must stay six feet, eave to eave, from any other structure on the site. Its entrance and outside stairs, on a house lot, may not be visible from the street (the public right-of-way) unless that rule would prevent the unit.

The hillside rule is the one place the code sets a size below the state floor. On lots in the hillside overlays served by a street "with a pavement width of up to 26 feet wide," a new ADU is capped at 800 square feet. Government Code 66321(b)(2) bars any maximum size "less than either of the following: (A) Eight hundred fifty square feet," or 1,000 square feet for more than one bedroom. Government Code 66314(a) does let a city designate areas for ADUs based on "the impact of accessory dwelling units on traffic flow and public safety," but the Pasadena section does not say it relies on that power. Under Section 17.50.275.A.1, state law prevails, so plan on the state minimums and confirm with the Planning Division before you design a hillside ADU larger than 800 square feet.

ADUs on Apartment Lots

A lot with an existing multi-family building may convert space "not used as livable space, including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, or garages" into ADUs: at least one, and up to 25 percent of the existing units in the building. In a mixed-use building, space used by the commercial part may not be converted. The same lot may also add "not more than eight detached ADUs," but never more ADUs than the existing units on the lot. A lot with a proposed multi-family building may have up to two detached ADUs.

Detached ADUs on these lots need four foot rear and side setbacks and may be 16 feet tall, or 18 feet when the apartment building is more than one story or the lot is within a half mile walk of a major transit stop or high-quality transit corridor, with two more feet allowed to match the roof pitch near transit. For the ADU rules, Pasadena defines multi-family as "two or more attached units, existing or proposed," so an attached duplex counts.

Height, Setbacks and Historic Properties

• Attached ADU. No higher than 25 feet or the zone limit, whichever is less, and up to two stories.
• Detached ADU, 16 feet. In the hillside overlays, in landmark or historic districts where it is visible from the street, and for an Exemption ADU in the front setback. This rises to 18 feet on a site with a multistory building or within a half mile walk of major transit.
• Detached ADU, 18 feet. All other detached ADUs, two stories allowed, plus two feet near major transit to match the roof pitch of the house.
• Front setback. A new ADU larger than 800 square feet must meet the zone's front setback.
• Side and rear. Four feet for new ADUs and for additions to conversion ADUs. A structure rebuilt in the same place with the same size and height needs no setback except for fire safety.

Section 17.50.275.D.2 adds a rule for historic property: a non-exemption ADU on an individually designated historic property or in a landmark or historic district "shall not be visible from the public right-of-way, unless this requirement prevents the creation of the unit." The historic districts page covers the rest of the review in those districts.

ADU Parking, Rentals and Sale

An ADU on a house lot needs one parking space, which "may be provided as covered, uncovered, or as tandem parking on an existing driveway." No parking is required for an ADU on a multi-family site. On a house lot the space is waived for an Exemption ADU, a site "within one-half mile walking distance of a public transit stop," an ADU inside existing space, a property in a historic district, a lot within one block of a car share pick-up spot, or an ADU filed together with a new house that also meets one of those tests. If a garage is torn down or converted to make the ADU, the lost parking does not need to be replaced. The ADU must share the house's driveway; a second driveway is allowed only from an alley that serves the site, and only when replacement parking is required.

Any rental of an ADU or junior ADU legally created on or after January 1, 2017 "shall be longer than 30 days." An ADU may not be sold apart from the house unless a qualified nonprofit corporation builds it under Government Code 66341.

Junior ADUs

A junior ADU sits inside the walls of a house, which can include an attached garage or other attached space that was not living area. Section 17.50.275.E sets its rules: a maximum of 500 square feet; an efficiency kitchen with a cooking appliance, a food preparation counter and storage cabinets; a separate entrance; and a bathroom of its own or a shared one. If it shares the bathroom, it needs an inside door to the main living area, and "either the primary unit or the Junior ADU shall be owner-occupied." The owner must then record a covenant, a notice on the title that tells later owners about these rules, before the building permit is issued. Owner occupancy is not required when the owner is a government agency, land trust or housing organization. These rules match Government Code 66333(b).

SB 9 Two-Unit Developments

Table 2-2 permits "Up to two primary residences (Two-Unit Developments)" in every RS district. Section 17.22.050.G says attached or adjacent homes are permitted if they meet building code standards, "are designed sufficient to allow separate conveyance," meaning each could be sold on its own, and meet the zone standards or the extra standards in the section's table. The table applies to a second primary home next to an existing one, or to two new homes on a vacant lot.

Source: Pasadena Municipal Code, Sec. 17.22.050.A and G, Supplement 79.

Each project must include at least two trees: a retained tree of at least 19 inches in trunk diameter, a retained tree from the City's Native and Protected Species list, or a new 24-inch box tree from that list. Section 17.22.050.H adds a garden rule: each Two-Unit Development needs "a landscaped open space area as its central focus," a rectangle at least 20 feet in each direction; a garden at ground level with no parking below must be at least half planted. Where the garden, setback or size rules would prevent an 800 square foot home, "the plan check review process shall only allow deviations sufficient to accommodate such development." That matches Government Code 65852.21, which bars standards that would keep either unit from being at least 800 square feet.

If an existing home will be torn down, the applicant must follow the state replacement housing rules. Short-term rentals of less than 30 days are prohibited, and a lot made by an SB 9 split may hold "only two units of any type," with no new ADUs. The lot size and subdivisions page covers the split itself.

Where Pasadena's Text and State Law Differ

• Historic districts. Section 17.22.050.G bans Two-Unit Developments on historic sites and on "sites that fall within historic districts," including landmark districts. Government Code 65852.21(a)(5), as amended by SB 1426 effective June 30, 2026, excludes "A contributing structure within a historic district" and individually listed or landmark parcels. A contributing structure is a building that adds to a district's historic character. The statute sets the limits, so it controls for a non-contributing property inside a district.
• Eaton Fire area. Section 17.22.050.G still prints a ban on Two-Unit Developments in very high fire hazard severity zones within the 2025 Eaton Fire boundary. Ordinance No. 7474, adopted August 3, 2026, repealed the ordinances behind it, Nos. 7455 and 7457. A July 20, 2026 staff report says SB 9 applications there "will be processed... as appropriate" after the repeal.
• Hillside ADU size. The 800 square foot cap on narrow hillside streets sits below the 850 square foot floor in Government Code 66321(b)(2), as described above.
• Window rule. The printed code applies the upper-floor window rule to junior ADUs; the June 2026 staff summary says Ordinance No. 7471 moves it to non-exemption ADUs.

Pasadena is a charter city, but SB 9 defines a local agency as a city "whether general law or chartered," and the City writes its own SB 9 rules into its code. The SB 9 page explains the court case some other charter cities brought against the law.

Where to Go Next

Related on VanPlex: the Pasadena overview, the California ADU law page and the SB 9 page.

Frequently Asked Questions

Official sources (checked October 2026)