SB 9 in Anaheim: Max Unit Sizes, Lot Split Rules, and What Single-Family Owners Need to Know
If you own a single-family home in Anaheim and you've heard about SB 9 but haven't dug into what it actually allows — or doesn't — this is the post for you.
Senate Bill 9 became effective January 1, 2022. It requires cities to allow two residential units on single-family zoned lots by right, and to ministerially approve the subdivision of one single-family lot into two separate parcels. Anaheim adopted its own implementing ordinance to comply with state law, and in several cases added requirements that are more restrictive than what SB 9 requires at the state level.
There are two separate paths under SB 9, and they work differently. Understanding which one you're pursuing — and what size and design rules apply to each — is where most homeowners get confused.
Path 1: Two-Unit Development (No Lot Split)
Under Anaheim's Two-Unit Development code, a property owner in a single-family zone can build or convert a second unit on their existing lot without subdividing it. Both units stay on one parcel.
Maximum unit size: 800 square feet. This is the floor that state law requires cities to allow, and Anaheim chose to make it the ceiling as well. SB 9 doesn't set a maximum — it only requires that cities permit at least 800 square feet. Anaheim's ordinance locks the maximum at that same number, so you cannot build a Two-Unit Development unit larger than 800 square feet under this pathway.
Minimum unit size: 400 square feet. The state law doesn't specify a floor, so Anaheim set one — roughly the size of a two-car garage — to ensure new units are actually livable rather than token square footage.
Here's what that looks like in practice: you can have two units on your lot, each between 400 and 800 square feet. That's the box you're working in.
Height
For attached Two-Unit Development — meaning the second unit is physically connected to the primary dwelling — the height limit of your underlying zone applies. Anaheim didn't add a separate cap here because an attached unit visually reads as an addition to the main house, so it's subject to the same rules.
For detached Two-Unit Development, the maximum height is 16 feet or the height of the main dwelling unit, whichever is greater. That said, the Planning and Building Director has discretion to allow additional height up to the zone's limit if you can demonstrate it's necessary to actually achieve the 800 square foot minimum. In other words, if your lot configuration makes it impossible to hit 800 square feet at 16 feet, you can make that case.
Setbacks
Front: Whatever the underlying zone requires
Side: 4 feet
Rear: 4 feet
The four-foot side and rear setbacks mirror what SB 9 mandates as a maximum restriction. Front setbacks defer to your zone's existing standards so that the street scene stays consistent.
Separation Between Units
If you're building two detached structures, they must maintain a 10-foot separation between them. This is Anaheim's added requirement — state law doesn't specify a distance, only that separation can't be the sole reason a project is denied.
Parking
One parking space is required per unit. The exemption: if your property is within a half-mile of a high-quality transit corridor or major transit stop, or within a half-mile of a car share vehicle, additional parking cannot be required.
Other Requirements
Each unit must have independent exterior access — they can't share a single entrance
The new unit may be separately metered for gas, electricity, communications, water, and sewer; for new construction, Anaheim Utilities may require a direct connection
Design standards mirror the single-family zone — the new unit has to meet the same articulation requirements as any single-family home in the city
No maximum lot coverage requirement applies to Two-Unit Developments — Anaheim eliminated it to streamline approvals
Path 2: Urban Lot Split
The Urban Lot Split is a different animal. Here, you're not just adding a second unit — you're actually subdividing one single-family parcel into two separate lots, each of which can then have up to two units on it. Done fully, a single-family lot could theoretically produce four units total. California recently completed its first ADU sale as a separate, independently titled home, which gives some sense of where the Urban Lot Split pathway is headed long-term.
Anaheim's implementing code for Urban Lot Splits is more restrictive in several ways.
Minimum lot size after the split: Each new parcel must be at least 1,200 square feet or 40% of the original lot size, whichever is greater. This is the state law floor, and Anaheim adopted it without modification.
Lot frontage: Every new lot created by an Urban Lot Split must have frontage directly onto a public or private street. Alleys don't count. This is a city-added requirement — state law defers the frontage question to municipalities.
Lot width: Each lot must be at least 25 feet wide abutting the street. Again, this is Anaheim's own standard — SB 9 doesn't specify a minimum width.
Owner occupancy: You must have occupied the property as your primary residence for at least three years before an Urban Lot Split application will be approved. This is required by state law and Anaheim enforces it.
Rental term minimum: Any rental on an Urban Lot Split parcel — or on a Two-Unit Development — must be for a period greater than 30 days. Short-term rentals are not permitted under either SB 9 pathway.
Utility service: Each lot created by an Urban Lot Split must have its own separate utility service — it can't share a connection with the adjacent parcel.
Properties That Don't Qualify
Not every Anaheim single-family lot is eligible for SB 9. State law excludes the following outright:
Properties developed with affordable housing
Properties that were tenant-occupied within the last 3 years (this applies even if the tenant has since moved — if someone was renting the unit within that window, SB 9 does not apply; understanding how tenant history affects your options is critical before you list or develop)
Properties where a rental was terminated within the last 15 years (i.e., an Ellis Act eviction)
Hazard waste sites
Sites subject to the Natural Community Conservation Planning Act
Properties under a conservation easement
Properties in a historic district
There are also conditional exclusions — properties in these zones may be prohibited unless specific criteria are met:
Very High Fire Hazard Severity Zone
Earthquake Fault Zone
Special Flood Hazard Zone
Regulatory Floodway
And Anaheim added one more category: sewer-deficient areas. Properties on parcels with known sewer deficiencies are already prohibited from ADU and JADU development in Anaheim, and the city intends to apply the same map when evaluating SB 9 applications. If the building official determines that a development would create a specific, adverse impact on public health — and sewer capacity is the city's primary concern here — the project can be denied.
What This Actually Means for Anaheim Owners
The Two-Unit Development pathway is the more accessible of the two. You don't need to subdivide, you don't need three years of owner-occupancy, and you can move on plan check fees rather than a separate application process. The 800 square foot cap is tight, but it's workable — especially for detached units in larger backyards.
The Urban Lot Split unlocks more density potential, but it comes with owner-occupancy requirements, lot dimension constraints, and the separate utility connection requirement that adds cost. It's a longer-horizon play, and the three-year clock means you can't buy a property and immediately pursue the split.
For investors looking at Anaheim, the Two-Unit Development pathway is worth understanding before you make an offer on a larger single-family lot. The income potential from a permitted second unit — even at 800 square feet — is real, and what that income does to your property's valuation when it's time to sell is something most buyers aren't pricing in yet. It also matters for how you finance it: lenders count ADU rental income differently depending on the loan type, and knowing which program gives you the most purchasing power changes the math on whether this pencils.
If you want to see how SB 9-eligible lots are currently moving in Anaheim and what buyers are actually paying, the Anaheim ADU market data for August 2026 has the active listings and recent closings worth tracking.
Dylan Serna is an ADU specialist real estate agent serving buyers and sellers across Orange County and LA County. Questions about SB 9 eligibility on a specific Anaheim property? Reach out here.
