What does San Gabriel's ADU ordinance mean for your property?

An ADU plan can become part of your San Gabriel sale or purchase before its limits are clear. Ordinance No. 706 as adopted in May 2024 provides specific rules for size, height, fire access and historic districts, but it isn’t confirmation of what applies to your property today.

Status as of October 28, 2026: The current text of section 153.047, later amendments and cross-referenced provisions remain unverified. Current city code and state law may differ from the adopted ordinance.

This is general information and not legal advice.

What does the ordinance allow on a residential lot?

Ordinance No. 706 as adopted in May 2024 allows one ADU plus one junior ADU on a lot in a single-family zone with a single-family structure.

For multifamily structures, its table allows two detached ADUs and ADUs within existing multifamily units up to a quarter of the existing units, or one unit if that is more. Non-habitable space, including boiler rooms, storage rooms, attics, basements and garages, may be converted.

The ordinance says the Community Development Director or designee permits ADUs and junior ADUs when an application meets its listed requirements. That makes the proposed unit type and existing structure important starting points.

The broader ADU rules provide context for the distinction between an ADU and a junior ADU. Related Learn topics include Highland’s ADU ordinance, septic and fire zones and Paramount’s historic preservation ordinance. For a sale or purchase, keep the May 2024 allowances separate from any claim that a particular property has an approved additional unit.

What does the fire safety condition say?

The ordinance’s fire safety subsection sets both a fire lane condition and a minimum fire flow condition, with an exception.

Its wording says new ADUs and junior ADUs may only be on a residential lot with at least a ten-foot-wide fire lane within 150 feet of the subject property and minimum fire flow of 1,000 gallons per minute.

The exception covers ADUs and JADUs exempt from separate planning review and cross-refers to section 153.047(M). The ordinance text should be checked against the current code.

Status as of October 28, 2026: Whether this condition applies or is enforceable under current state law remains unverified. The adopted text does not establish which lots meet it or who certifies compliance.

Can an ADU be built in a historic district?

ADU construction is allowed in designated historical districts under the ordinance, but the ADU must not be visible from the public right-of-way.

That is a visibility condition, not a blanket prohibition. The distinction matters when considering a proposed unit’s placement. The adopted text does not identify the districts or establish that any particular property falls within one.

Under the ordinance, demolishing a detached garage that is being replaced by an ADU is reviewed with the ADU application and issued at the same time, and does not need written notice or a posted placard unless the property is in an architecturally and historically significant district.

We were helping a San Gabriel owner explore an ADU behind an older house. She had enough yard space, but the property’s age and the access along the side of the house raised separate questions about historic review and fire-lane requirements. We had to look beyond the basic ADU size rules before telling her whether the idea was practical.

How large can an ADU or junior ADU be?

Detached ADU limits in the May 2024 text are 850 square feet for a studio or one-bedroom unit and 1,000 square feet for a two-bedroom unit.

The maximum is two bedrooms. An attached ADU is limited to half the main dwelling’s size or the applicable 850- or 1,000-square-foot figure, whichever is less.

The ordinance also says lot coverage, floor area ratio, open space and minimum lot size standards cannot prevent an ADU of at least 800 square feet. That protection belongs alongside the size limits, rather than being left out of a discussion about a small lot.

A junior ADU has a different limit: 500 square feet, inside the existing walls, with an efficiency kitchen. The ordinance allows one per lot with a single-family dwelling.

These are the adopted ordinance’s dimensions. They don’t confirm a proposed floor plan or the current treatment of a specific property.

How do height and setbacks affect a proposed unit?

For height, Ordinance 706 uses 16 feet measured from the lowest adjoining grade, with specified taller allowances.

It allows 18 feet within half a mile walking distance of a major transit stop or high-quality transit corridor, plus two feet for matching roof pitch. It also allows 18 feet with an existing or proposed multifamily multistory dwelling. An attached ADU may reach 25 feet, with no more than two stories.

A two-story detached ADU is allowed only when an 800-square-foot ADU cannot be achieved as a one-story unit.

Side and rear setbacks are four feet. Separation is six feet from another building and four feet between eaves, chimneys and bay windows. Detached units meet the front setback unless that prevents an 800-square-foot ADU.

What does the ordinance say about parking and design?

The parking provision calls for one parking space per bedroom or unit, whichever is less, and lists exceptions.

Those exceptions include locations within half a mile walking distance of transit, historic districts, and locations within one block of a car share vehicle. They also cover situations where on-street permits are required but unavailable to the occupant, or the application accompanies a new dwelling on the same lot.

For design, the exterior is to match the main dwelling’s form, materials, color, finishes, roof forms and windows. An attached unit’s separate entrance belongs on the side or rear, not the front.

The ordinance describes ministerial review without a hearing within a 60-day window. Its subsection Q identifies specified existing-space conversions and a detached new ADU up to 800 square feet and 16 feet high with four-foot setbacks.

Can the additional unit be rented or sold separately?

ADU rental is permitted under the ordinance, while separate sale is restricted, with state-law exceptions addressed in its covenant language.

The ordinance’s wording differs between provisions. One says the ADU shall not be sold but may be rented. The recorded covenant language says it may not be sold separately unless conditions under the cited state law are met. An owner should ask what applies today.

The covenant is recorded when a building permit is issued and bars rentals shorter than 30 days.

For a junior ADU, a recorded deed restriction requires owner occupancy in either part and prohibits sale separate from the house.

Status as of October 28, 2026: Current separate-sale provisions and any later changes remain unverified.

The short version

Ordinance No. 706, adopted May 7, 2024, gives you specific ADU dimensions and conditions, while today’s applicable rules still need confirmation.

For a proposed unit, focus on its type, size, placement and review path. Keep the fire safety exception and historic-district visibility condition in view. Neither an allowance in the adopted ordinance nor a proposed layout establishes approval for a particular property.

To consider your property’s value alongside these questions, start with the home value tool.