Starting 2027, an SGV House Lot Can Get Two Detached ADUs and Lower Fees on Larger Ones

What changed

If you own a house in the San Gabriel Valley, the backyard unit rules change on January 1, 2027. Your city will have to approve two detached backyard units on a single-family lot, up from one. Impact fees on larger units will also shrink.

Two bills signed on September 29, 2026 make these changes. An ADU (accessory dwelling unit) is a second, smaller home on the same lot as a house.

• AB 956 (Chapter 791) covers detached, newly built ADUs on a single-family lot. A city must now approve two of them, up from one.
• SB 1117 (Chapter 809) changes impact fees on ADUs larger than 750 square feet. Impact fees are one-time charges on new construction. Cities and districts use them to pay for parks, roads, and similar services.

Neither bill changes your city's zoning map.

A charter city runs its local affairs under its own charter, not only the state's general city rules. Charter cities sometimes argue that a state rule doesn't bind them. SB 1117 says its fee rule is a statewide concern, so it applies to charter cities too. The SGV's charter cities are Alhambra, Arcadia, Industry, Irwindale, Pasadena, Pomona, and Temple City.

AB 956: two detached ADUs, approved by staff

State law keeps a list of ADUs a city must approve, in Gov. Code § 66323. Units on that list get ministerial approval. That means staff must sign off if the plans meet written standards, with no hearing. From 2027, the list includes two detached ADUs on one lot. Both must be new buildings. Turning an existing structure, like a garage, into an ADU falls under a different rule on the same list. The lot must have an existing or planned single-family home.

A setback is the required distance between a building and the property line. For these units, side and rear setbacks can be no more than 4 feet. The city may limit each unit to 800 square feet of living space.

The city may also limit height, using the state's ADU height rule in Gov. Code § 66321. On a single-family lot, that limit is 16 feet in most places. Within a half-mile walk of a major transit stop, it is 18 feet, plus 2 feet more for a roof that matches the house's slope.

The bill includes one trade-off. If a lot uses both detached ADUs, the city can skip approving a junior ADU (JADU) there. A JADU is a unit of up to 500 square feet made from space inside the house itself.

AB 956 and HOA rules

CC&Rs are the recorded rules of a planned development or HOA. Since 2020, Civil Code § 4751 has voided, or canceled, CC&Rs that effectively ban or unreasonably restrict ADUs on single-family lots. That part is old law. HOAs can still set "reasonable" restrictions: rules that don't unreasonably raise the cost or block construction.

What AB 956 changes is which lots are covered. The old wording covered lots zoned for single-family use. The new wording covers lots zoned to allow single-family use. AB 956 makes the same change to Civil Code § 714.3, which covers deed restrictions outside HOAs.

SB 1117: fees only on the space above 750 square feet

The change is in Gov. Code § 66311.5(c). State law already barred impact fees on an ADU of 750 square feet or less. For a larger ADU, the fee had to be scaled to its size compared with the main house. It applied to the whole unit.

From 2027, the rule changes for lots with up to two ADUs. The fee on an ADU over 750 square feet is still scaled to the main house. It now applies only to the area above 750 square feet. An 800-square-foot ADU would be assessed on 50 square feet. A lot with more than two ADUs keeps the old rule. There, each larger ADU is assessed on its full size.

Utility connection fees and capacity charges are not "impact fees" under this section. SB 1117 does not reduce them.

Each city applies the new rule to its own fee schedule. Ask your city's planning or building department for its current ADU fees.

If you own the house

This matters most on a standard lot with room behind the house. Two detached units are now on the must-approve list. Your city may limit each one to 800 square feet.

The fee on each is figured only on its last 50 square feet, not the whole unit, and still scaled to the size of your house. That can change whether a second rental or a family unit makes financial sense.

Units of 750 square feet or less already paid no impact fee. The change is for larger units. Take one 1,000-square-foot ADU:

• Before 2027, the fee was figured on all 1,000 square feet.
• From 2027, it is figured on the 250 square feet above 750.

Your city may also update its own ADU rules before January 1. Ask which rules it will use for your permit.

If you live nearby or rent

Your neighbor can now build two detached units in the backyard, with no hearing and 4-foot setbacks. Before 2027, the must-approve limit was one.

In an HOA community, the board loses some room to restrict ADUs. For renters, more small detached units add rental supply in single-family neighborhoods.

How they passed

AB 956 passed with a few "no" votes:

• Assembly, May 2025: 58-4
• Senate, August 2026: 27-6
• Assembly vote on the Senate's changes: 60-2

SB 1117 passed with zero "no" votes:

• Senate, May 2026: 37-0
• Assembly, August 2026: 70-0
• Senate vote on the Assembly's changes: 38-0

Who to contact

Owners, builders, and neighbors can all use these.

Your city's building or planning department (both). Processes the ADU permit itself and sets local ADU fees within the state limits above. Contact information is on your city's own website.

LA County Department of Regional Planning (both). The planning office for unincorporated areas such as Altadena, Hacienda Heights, and Rowland Heights. Phone: (213) 974-6411. Email: info@planning.lacounty.gov. Website: planning.lacounty.gov.

California Department of Housing and Community Development (HCD), Housing Accountability Unit (both). Reviews reports that a city's ADU rules or permit practice conflict with state law. It accepts requests from anyone. Email: HAUPortal@hcd.ca.gov. Website: hcd.ca.gov/hau/portal.

Before you act

This article is general information, not legal advice. Laws change, and every property is different. Before you act, talk to a licensed California real estate attorney. For tax questions, also talk to a CPA.