Everything homeowners need to know about building an accessory dwelling unit in Pasadena - size limits, setbacks, permits, and how hillside terrain and historic districts change the picture.
Last verified: August 2026
6/10 · ADU-friendly, with local friction
1,200 sq ft*
Max ADU size
18 ft*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Pasadena Municipal Code Section 17.50.275 (Accessory Dwelling Units) and California's statewide ADU law (Government Code Sections 66310-66342) for general reference only, and it is not legal advice. Pasadena's ordinance has been amended repeatedly in recent years (see ordinance history below). Always confirm current requirements with Pasadena Planning & Community Development before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
New construction, parcels under 10,000 sq ft
800 sq ft or 50% of the primary home's living area, whichever is less
Up to 18 ft / 2 stories outside the Hillside Overlay and street-visible Historic/Landmark Districts; 16 ft where those overlays apply
Minimum ADU size is 150 sq ft
New construction, parcels 10,000 sq ft and up
1,200 sq ft or 50% of the primary home's living area, whichever is less (up to 75% with an affordability covenant in RM zones)
Generally no added setback beyond what the existing structure already has
Junior ADU (JADU)
500 sq ft
Same as the primary structure
Built within the existing walls of the home
Allowed zoning districts & overlays
ADUs are allowed on lots zoned for single-family or multifamily residential use, citywide, through PMC 17.50.275. Two overlays change what you can build: on Hillside Overlay parcels (HD, HD-1, HD-SR), newly constructed ADUs are not permitted at all, only conversions of existing structures; and on parcels within a Landmark or Historic District that are visible from the public right-of-way, new construction also needs a Certificate of Appropriateness from the Cultural Heritage Commission, which typically adds several weeks of review for exterior materials and design. Confirm your parcel's overlay status with Planning & Community Development before you design.
Additional standards
Setbacks, parking & other rules
Setbacks
The state-guaranteed 800 sq ft pathway gets 4 ft side and rear setbacks by law. Pasadena's own standard for larger newly constructed ADUs requires the underlying zone's setbacks, including a rear setback of roughly 10 ft in many cases; converted ADUs generally need no added setback.
Parking
1 space per unit (covered, uncovered, or tandem), waived within a half-mile of transit, for conversions of existing space, in preferential parking permit districts that don't offer permits to the ADU, or where a car-share vehicle is available within a block. State law also exempts the smallest, state-guaranteed ADUs from any parking requirement, something HCD flagged Pasadena's ordinance for not clearly stating.
Units per lot
State law entitles a single-family lot to combine 1 ADU and 1 JADU. Pasadena's code text has at points read as capping this at a single "exemption ADU," a gap HCD flagged in February 2025 that the city addressed in corrective amendments adopted January 2026. Multifamily lots can add more, including up to 8 detached ADUs under SB 1211.
Owner-occupancy
Not required for ADUs, permanently eliminated statewide by AB 976 effective January 1, 2024. JADUs generally still require the owner to occupy either the primary residence or the JADU, per state law.
Building code
Must meet the California Residential Code as locally adopted by Pasadena
Historic District review
New construction and additions visible from the public right-of-way in a Landmark or Historic District need a Certificate of Appropriateness from the Cultural Heritage Commission, focused on material compatibility, window types, siding, and roof form
Ordinance history
How Pasadena's ADU rules got here
2017Statewide by-right ADU law takes effect. California Government Code Section 65852.2 begins requiring cities, including Pasadena, to approve most ADUs ministerially, without discretionary review.
Apr 2024Pasadena adopts Ordinance No. 7420. Adopted April 15, 2024, it rewrote PMC 17.50.275 for the prior round of state ADU reforms, including the Hillside Overlay and Historic District rules described above.
Jan 2025The Eaton Fire strikes the region. The January 2025 wildfire devastated Altadena and parts of northern Pasadena, red-tagging homes across the area and putting ADU-enabled rebuilding on the city's agenda for the year that followed.
Feb 2025HCD finds Ordinance No. 7420 non-compliant. A findings letter dated February 26, 2025 identified six issues, including a one-"exemption ADU"-per-lot cap that conflicts with state law's unit-combination rights, a front-setback restriction on 800 sq ft attached ADUs, and a parking requirement not properly excluded for state-guaranteed units. The city had until March 28, 2025 to respond.
Jan 2026City Council adopts corrective amendments. Adopted January 26, 2026, the amendments to PMC 17.50.275 addressed HCD's six findings, including the SB 1211 multifamily unit-count update that took effect statewide on January 1, 2025.
2026Fee reductions roll out; another ordinance in progress. The city announced reduced plan check, permit, and impact fees for most ADUs, with deeper discounts for Standard Plans and affordability agreements. A further ADU ordinance had its first reading on June 15, 2026, so the rules are still actively evolving.
Worth knowing: Pasadena's ADU ordinance has been a moving target. A 2024 rewrite drew a six-point HCD non-compliance finding in early 2025, corrected about a year later, with yet another ordinance introduced in mid-2026. If you're reading an online guide that's more than a few months old, double-check its numbers against Planning & Community Development directly, especially anything involving the Hillside Overlay or a Historic District.
Permit process
How Pasadena ADU permitting works
1
Pre-application check
Confirm your zoning, lot size tier (over or under 10,000 sq ft), and whether your parcel sits in the Hillside Overlay or a Historic District, with the Pasadena Permit Center, (626) 744-7311.
2
Prepare your plan set
You'll need a site plan, floor plans and elevations, and existing floor plans if you're using the 50%-of-primary-home option; Historic District projects visible from the street also need exterior material and design details.
3
Certificate of Appropriateness (if applicable)
Street-visible new construction or additions in a Landmark or Historic District go through Cultural Heritage Commission design review first, typically 4-6 weeks.
4
Submit through SmartGov
File your building permit application online through the city's SmartGov portal.
5
Ministerial plan review
State law requires a decision within 60 days of a complete application; the permit is deemed approved if the city misses that deadline.
6
Building permit & inspections
Pull your building permit, begin construction, and schedule the standard framing, plumbing, electrical, and final inspections.
Ask about the city's ADU Standard Plans Program for a faster path than a fully custom design; as of 2026, most of its free pre-approved designs are reserved for properties red-tagged by the Eaton Fire, with one general-use studio plan still available. Fees and timelines are approximate - confirm current figures with Planning & Community Development.
Budgeting
What it costs to build an ADU in Pasadena
Garage conversion
Roughly $90,000-$200,000, the least expensive path since the shell already exists
New detached ADU
Roughly $180,000-$400,000+ for a code-compliant, freestanding unit; hillside sites often add grading and geotechnical costs on top
City fees (2026 reductions)
Most ADUs see roughly a 25% reduction in plan check, permit, and impact fees under the city's 2026 program; projects using a Standard Plan or an affordability Housing Agreement can see savings of over 50%
Construction & Demolition deposit
A flat, refundable $1,000 deposit applies to all ADUs
Certificate of Appropriateness (Historic Districts)
Adds review time, typically 4-6 weeks, for street-visible new construction; budget for design consultation if your parcel is in a historic district
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, slope, finishes, and whether Hillside Overlay or Historic District review applies. San Gabriel Valley land and labor costs push Pasadena toward the upper end of the statewide range.
Before you apply
Tips for a smooth approval
Check your Hillside Overlay status before you design a detached unit. New construction isn't permitted there at all, only conversions of existing structures.
Budget extra weeks if you're in a Historic District. A Certificate of Appropriateness is required for street-visible new construction, on top of the standard building permit review.
Ask about the 2026 fee reductions. Standard Plans and affordability Housing Agreements can cut your city fees by more than half.
Confirm your lot size before you set your size expectations. The cap steps up from 800 sq ft to 1,200 sq ft at the 10,000 sq ft lot-size mark.
Make sure you're working from the January 2026 corrective amendments. Pasadena's ADU rules changed materially in response to HCD's findings, and some older guides still describe the pre-2026 version.
FAQ
Common questions
Do I need to live on the property to build an ADU in Pasadena?
No. California's AB 976 permanently eliminated owner-occupancy requirements for ADUs statewide as of January 1, 2024. Junior ADUs generally still require an on-site owner.
Can I build a detached ADU on a hillside property?
Generally, no. Newly constructed ADUs are not permitted on parcels within Pasadena's Hillside Overlay District (HD, HD-1, HD-SR). Converting an existing structure, like a garage, is typically still an option. Confirm your parcel's overlay status with Planning & Community Development.
What if my property is in a historic district?
New construction or additions visible from the public right-of-way need a Certificate of Appropriateness from the Cultural Heritage Commission, which reviews exterior materials and design and typically takes 4-6 weeks. Converted ADUs generally face fewer added requirements.
How many ADUs can I build on one lot?
State law entitles a single-family lot to 1 ADU plus 1 JADU, combinable. Pasadena's own ordinance text has lagged behind that standard at points, most recently corrected in January 2026. Multifamily lots can add more, including up to 8 detached ADUs on qualifying properties under SB 1211.
Do I need extra parking for an ADU?
Usually one space, unless your project qualifies for an exemption, such as being within a half-mile of transit or a conversion of existing space. State-guaranteed 800 sq ft ADUs are exempt from any parking requirement under state law.
How long does the permit process take?
State law requires a ministerial decision within 60 days of a complete application, and the permit is deemed approved if Pasadena misses that deadline. Projects needing a Certificate of Appropriateness should budget an additional 4-6 weeks ahead of that window.
How much does an ADU cost to build in Pasadena?
Garage conversions tend to run roughly $90,000-$200,000, and new detached units roughly $180,000-$400,000 or more, based on local contractor estimates and regional reporting. The city's 2026 fee reductions cut plan check, permit, and impact fees by roughly 25% for most projects, and more for Standard Plans or affordability agreements.
Is Pasadena's ADU ordinance fully compliant with state law?
The city adopted corrective amendments in January 2026 specifically to address the six issues HCD identified in a February 2025 findings letter, and a further ADU ordinance had its first reading in June 2026, so the rules are still evolving. In the meantime, homeowners are entitled to state law's ministerial approval path regardless of where the local ordinance stands.
Does the Eaton Fire affect ADU rules in Pasadena?
The January 2025 Eaton Fire devastated Altadena and parts of northern Pasadena. As of 2026, most of the city's free pre-approved ADU Standard Plans are reserved for properties that were red-tagged in the fire, part of a broader push to help displaced homeowners rebuild efficiently.
