Updated: 6 days ago
An SB9 permit adds the options of creating a duplex and/or doing a lot split to the expanded ADU guidelines that have been put out by the State, but it is often significantly more complex than a simple ADU application.
In theory, SB9 allows an existing lot to be expanded up to 4 units, including 2 primary homes and 2 ADUs, depending on lot size and access. There are also setback rules requiring the ADU and primary dwelling to be 10 feet apart unless the main house is less than 800 SF. And the 8’ side and rear setbacks can be similarly reduced to 4’ if the primary dwelling is under 800 SF.
To qualify for SB9, the property needs to be in a residential zone. You can’t get an SB9 in a historic district or with a house listed in the historic registry, and the resulting project can’t include commercial uses. And unlike the new ADU guidelines which can’t be stopped in a PUD or condo development, you are required to get an approval letter from your HOA for an SB9 project.
There are also occupancy constraints, such as the Just Cause Eviction rules which apply for duplexes. Under SB 1482, an owner applicant is exempt if living on-site and occupying a SFR. Conversely, if the residence has been a rental in last 3 years, it is not eligible for SB9. And you are also not allowed to increase your housing by more than 25% if the property is subject to rent control, has been used for low-income housing, or has been a rental for longer than the 3 preceding years.
SB9 splits also can’t be done on farmlands, wetlands, or parcels with protected species or conservation easements. Splits are allowed in areas of High Fire Responsibility, Earthquake Fault, and Hazardous Waste Zones, but the resulting parcels must meet current guidelines. Only parcels within the Urban Services Line are eligible, and the resulting lots can’t result in less than 1 acre, except if on public water, in which case you can go down to a 15,000 SF minimum Net Developable Area. For properties served by septic or constrained by water moratorium, your ability to add units will rely on getting additional credits and upgrades to your current fixtures and systems.
Anything in the Coastal Zone requires an additional level of approval in the form of a Minor Coastal Permit, which is a Level 4 Administrative Review with no public hearing. There are also lot size requirements for the resulting parcel size to be the greater of 1200 SF or 40% of the total, with frontage of 50 feet or a 20-foot access corridor, which in some cases can be reduced to 12 feet, based on case-by-case evaluation. And in the Coastal Zone it is required to provide a parking spot for an ADU, but a Junior ADU doesn’t require one.
Most local jurisdictions offer a pre-screening process for a SB9 split to help determine whether your property is eligible, and how long this process takes plus the answers you get can vary greatly depending on the administration for where your property is located.