Can you build an ADU in your backyard in Pasadena?

What rights does state law give you to build an ADU in Pasadena?

California law sets what every city must allow on ADU setbacks, size, height, fees, and approval. A city can be more generous than the state. It cannot write rules that fall below this floor, even where its own size or lot coverage limits would otherwise say no, and a neighbor's objection is not grounds to deny a unit that meets the written standards.

Treat the list below as the current floor, not a ruling on your parcel. California has rewritten its ADU rules almost every year lately, and each round shifts a detail, so confirm every point with the city before anyone designs around it. The points that shape most projects:

• Approval is ministerial, so city staff check the plans against written standards and no public hearing is held.
• Local size and lot coverage rules cannot block an 800 square foot ADU with 4 foot side and rear setbacks.
• A detached ADU is generally allowed at least 16 feet of height, and more in some cases.
• An ADU under 750 square feet is exempt from impact fees.
• A junior ADU of up to 500 square feet can be created inside the existing house.

Which Pasadena ADU rules apply on top of state law?

The city's own ADU rules cover what the state leaves open: the maximum size, any height above the state minimum, and written design standards, which can address details such as roof form, windows that face a neighbor, and materials. Those local rules get revised as state law moves, so work from the city's current version rather than from what a neighbor built a few years ago.

Every ADU permit in Pasadena still runs through Planning and Community Development, with plan check at Building and Safety, where the drawings are held to the building code: structure, energy, fire separation near property lines, and how the unit connects to water, sewer, and power. Ministerial approval removes the public hearing. It does not remove plan check, corrections, or inspections.

Historic status is the Pasadena wrinkle. If the house is designated or sits in a landmark district, a new building on the lot can draw historic review, and that review can shape where the unit sits and what it looks like. Ask the city's planning counter about your property's status before design starts.

Garage conversion, attached, detached, or junior ADU: which fits?

Start from what the lot already has: a garage, unused ground next to the house, a deep yard, or spare rooms inside. A garage conversion ADU fits when the garage is sound, sits in a workable spot, and is something you can live without. On the older garages we see, the work is turning a car space into a room: a slab that often slopes toward the door, walls with no insulation, and a wide opening that becomes a wall with windows and an entry.

An attached ADU suits a lot where the buildable space sits right against the house, or where the backyard is too shallow for a separate building. It shares a wall with the house, so plan what it does to the light in the rooms on that side. A detached ADU needs the deepest yard, with room for the unit, its setbacks, and space between it and the house, and it is the type most shaped by the sewer and access questions below.

A junior ADU is carved out of the house you already have, usually from a bedroom near an outside wall, and no new structure goes up. The work is mostly inside: its own entry, a small kitchen, and a way to close it off from the rest of the house. State law sets what a JADU must include, so confirm the current list with the city. It suits a household with more house than it uses.

What on your lot decides where an ADU can go?

The sewer usually decides first. Waste from the new kitchen and bathroom has to run downhill to the sewer lateral, the pipe that carries the house's waste to the public sewer, so a unit in the low back corner of a lot that falls away from the street may sit too low to drain by gravity. A pump can solve that, but it adds equipment that needs power and upkeep, so we look for the spot the sewer can reach before anyone falls for a corner of the yard.

Next come the things that fence off parts of the yard. Easements, such as a strip reserved for utility lines, are recorded on the title report and can keep a building off that ground. Mature trees matter twice: their roots do not mix with footings and trenches, and some cities protect certain trees on private property, so ask before assuming one can come out. A slope can mean grading and retaining walls before there is a flat pad to build on.

Last is access, which is easy to overlook until the first delivery. Everything for a detached unit, from concrete to lumber to a small excavator, comes down the driveway or through the side yard, and an air conditioning unit, a gas meter, or a narrow gap between houses decides what can get back there. A tight path rarely stops a project, but it changes how we build and how long it takes.

Do you have to provide parking for an ADU?

Often you do not. State law limits the ADU parking requirements a city can impose: no parking can be required for an ADU within half a mile walking distance of public transit, and no replacement parking can be required when a garage is converted into an ADU. With bus routes and rail stations across the city, many lots fall inside that half mile, but confirm how the distance is measured from your address.

Outside those cases the city can still ask for a space, and state law lists a few other situations where it cannot, which the planning counter can walk you through. Even when no space is required, think about your own cars. Giving up a garage moves them to the driveway or the street, and Pasadena restricts overnight street parking, so check how that works on your block before the garage door comes off.

Can you rent it out, and do you have to live on the property?

Yes, you can rent an ADU, and the city cannot require you to live on the property to do it. Cities used to be able to require owner occupancy for an ADU, and state law has since taken that away, so you can live in the main house and rent the unit, move into the unit and rent the house, or rent both.

A junior ADU works differently. The owner has to live in either the main house or the JADU, which suits a family that is staying and makes a JADU a poor choice if you might someday rent out the whole property.

If you plan to rent, we would design for two households up front: separate entries, windows that do not look into each other, and a path to the unit that does not cross your patio. Renting also brings its own local rules, including limits some cities put on short stays, so ask the city what applies before you list the unit.

How is it different in Altadena and the cities next door?

The state floor applies to every accessory dwelling unit in the San Gabriel Valley; what changes at the city line is who reviews your plans and which local rules sit on top. Altadena is the one that catches owners out. It is unincorporated Los Angeles County, so an Altadena ADU goes through LA County, not the City of Pasadena, even though many streets run straight across the line.

Altadena lots tend to be larger, and many slope toward the foothills, which can make room for a detached unit while bringing grading and drainage into the plan. The county applies its own ADU standards above the state floor and revises them just as the cities do, so confirm the current version with LA County before design. Who reviews an ADU nearby:

• In Altadena, permits run through LA County Public Works, Building and Safety, on the EPIC-LA online portal.
• In South Pasadena, the city's own building department reviews ADUs, in a town with a strong preservation culture.
• In Arcadia, the City of Arcadia Building Services handles plan check and permits.
• In La Crescenta, most parcels are unincorporated county, but part of the community sits inside Glendale.

How do you check feasibility before paying for plans?

Check the few things that can stop an ADU outright before anyone draws. Our first visit on an ADU is a feasibility and zoning check: we walk the lot, find where the sewer and power come in, measure the path to the back, and list the questions only the city can answer.

The check ends in a clear yes, a yes with conditions such as a pump or a smaller footprint, a better fit as a garage conversion or junior ADU, or now and then a no. Any of those is worth knowing before a designer's clock starts. Most of the checks take a phone call, a trip to the counter, or an hour on site:

• Confirm which agency has jurisdiction over the parcel, because a mailing address does not always tell you.
• Ask the planning counter for your zoning, historic status, and the current ADU standards.
• Find where the sewer lateral leaves the lot and how deep it runs.
• Photograph the electric panel and meter so the added load can be checked early.
• Measure the narrowest point of the driveway or side yard, including gates.
• Have a land surveyor mark the property lines, since old fences do not always sit on them.