Key Rules At A Glance
- Maximum size: 1,200 square feet
- Side/rear setbacks: 4 feet
- Two story: Yes
- Building separation: 4 feet
- Soils Report: If on a hill or slope
- Building Verification Survey: Yes
- Coastal permit (in some areas): N/A
- Stormwater Mitigation: Yes
Number of ADUs Allowed in Alhambra
On single-family residential lots in Alhambra, you may build one ADU, either attached or detached, on your property. You can also build up to one JADU into the existing primary residence.
Multifamily property owners in Alhambra may convert at least one ADU, and additional ADUs not to exceed a maximum number equal to 25% of the existing units out of existing uninhabitable space. Ergo:
- From 2 to 7 units, you could convert existing uninhabitable space into one ADU
- From 8 to 11 units up to 2 ADUs
- From 12 to 15 units up to 3 ADUs
- And so on.
No more than two detached ADUs may be constructed on a multifamily lot in Alhambra.
ADU Alhambra – Size & Building Constraints
In Alhambra, the maximum size your detached ADU can be is 1,200 square feet. For multifamily lots, the maximum size can vary depending on the lot size. A 1-bedroom detached ADU must typically be a minimum of 850 square feet; a 2-bedroom detached ADU, a minimum of 1,000 square feet.
In Alhambra, the maximum size your attached ADU can be is 800 square feet, or 50% of the size of the main dwelling unit, whichever number is greater.
In the city of Alhambra, the maximum size your detached ADU can be is 1,200 square feet.
In Alhambra, an attached or detached ADU can be built to a maximum height of 25 feet.
In Alhambra, you can build a two-story ADU, either attached or detached.
In Alhambra, you can only build one ADU on a single-family property. This precludes homeowners from stacking ADUs, as it would require permitting for two ADUs, one on each story of a two-story structure.
Multifamily property owners can build up to two detached ADUs on their property. Since ADUs can be built to a maximum height of 25 feet, that is enough clearance to build a two-story structure, and you can stack ADUs in such a structure, one on each floor.
In Alhambra, you can only build one ADU on a single-family property. This precludes homeowners from building a single detached structure with two ADUs attached to each other, as it would require permitting for two ADUs on one property.
Multifamily property owners can build up to two detached ADUs on their property. A single detached structure with two ADUs attached to each other therefore may be permitted on multifamily property in Alhambra.
No, a JADU is defined as an ADU converted from existing space within the main structure of the primary dwelling unit. As such, it cannot be attached to an ADU.
Generally roof decks would be permitted on an ADU, but must meet the height restrictions for the zone. Roof decks cannot encroach into the required setbacks. As a rule of thumb, railings and access staircases above 42″ need to be included in height calculations.
In Alhambra the ADU must match the architectural design of the proposed or existing structure. This includes using the same exterior material, roof material, color, and architectural details of the main dwelling unit similar to a garage conversion.
ADU Setbacks in Alhambra
In the City of Alhambra, side and rear setback requirements for an ADU are at least 4 feet. All other setbacks must comply with ordinary zoning setback requirements. No additional setback requirements apply to existing structures that are converted into ADUs.
The front setback requirements depend on the zoning. Property in Residential Low Density (RL) zones have a minimum front setback requirement of 25 feet, while in Residential Medium Density (RM) zones, the minimum setback is either 20 feet or the average setback of the two adjacent properties, whichever is greater.
Alhambra rules stipulate a minimum separation of 4 feet between structures within a lot.
Yes, in Alhambra you can build an ADU anywhere on the lot, including the front yard, as long as it complies with setback requirements.
Additional Requirements in Alhambra
No, Alhambra does not require in-person submission of plans for an ADU. The Alhambra Planning Division offers an online permit portal that you can use to submit your plans online.
Yes, a soils report is typically required as part of the approval process for an ADU construction permit.
ADU landscaping is generally required to blend into existing landscaping and enhance the overall aesthetic appeal. No more than 45% of front or side yards is allowed to be “hardscaped” in the process of building an ADU or new parking (concrete, asphalt, impermeable material, etc.)
To receive permits for your ADU, plans must be submitted to the Alhambra Planning Division for preliminary review. The plans must then be sent to a variety of other County departments for clearance. The basic process is as follows:
- Submitting initial plans and fees
- Initial review of plans for correctness and obvious issues
- Detailed departmental reviews (structural, zoning, fire safety, utility, environmental, etc.)
- Corrections and re-submission
- Final approval
From submission to approval, the average turnaround time is about 60 days. For complicated plans it can be longer.
The Alhambra Planning Division may send inspectors periodically to check the progress of the project and verify that it is being constructed to plan.
Parking for Alhambra ADU
The parking requirements for residential property are one additional parking spot per ADU. Properties located within ½ mile of walking distance from a public transit stop or station may be exempt from parking requirements.
If a garage or carport is replaced with an ADU, property owners need not maintain a number of off-street parking spaces commensurate to the number of parking spaces eliminated by the garage conversion. The owner also need not add additional parking spaces if an existing structure or space within a structure is converted into an ADU or JADU.
If a parking space is required, it may be located within the setbacks and in an existing driveway as tandem parking. Parking spaces don’t need to be replaced when a garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU or converted to an ADU.
Additional City of Alhambra ADU Regulation Resources
Most newly constructed ADUs must comply with California Title 24 Building and Energy Efficiency Standards. If you submitted your permit application later than January 1, 2020, this means you must provide solar panels on new ADUs to offset their reliance on the grid. This does not necessarily mean the solar panels need to be installed on the ADU itself. They can be installed on the primary dwelling unit or a new or existing array.
Some exceptions may apply to certain ADUs. Possible exemptions include:
- A detached garage converted to an ADU.
- An ADU built wholly within or attached to the primary dwelling unit.
- Manufactured ADUs.
- ADUs with small or shaded roofs.
No, a separate electric and water meter is not required for an ADU. However, you may request one from the city.
Not necessarily. An ADU can be permitted under the existing address. If you want your ADU to have its own address, you can apply to the Mapping and Property Management Division (MPM) for a “½” address designation. In other words, if your address is 1234 Elm Street, your ADU could have a separate address of “1234½ Elm Street.”
If the ADU has its own driveway or direct street access, a new address will be required.
Low Impact Development (LID) is an approach to land development or redevelopment that seeks to preserve and conserve onsite water quality and natural features, with minimal detrimental effect to local waterways and ecosystems. The City of Alhambra requires LID for ADUs of 500 square feet or more.
Operating an Airbnb or short-term rental, ADU or otherwise, is prohibited by the City of Alhambra.
Since the City of Alhambra does not have its own rent control ordinance, California Assembly Bill 1482 applies to rental units 15 years and older. This caps rent increases to 5% plus inflation, or 10%, whichever is smaller.
You can use gas appliances in an ADU in the City of Alhambra as long as all building codes, safety standards, and installation guidelines are adhered to. The proper permits must be obtained, and requirements for safety and ventilation observed.
You are not required to put fire sprinklers in your ADU if the main dwelling unit is not required by law to have fire sprinklers.
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