City of Diamond Bar ADU
Regulations
Everything you need to know about building Accessory Dwelling Units (ADUs) in Diamond Bar, CA.
Overview
The City of Diamond Bar, CA, just passed a new ordinance making it easier for residents to build accessory dwelling units (ADUs) on their property. The goal of the regulation is to increase housing availability in the city while also providing residents with more flexibility in how they use their property.
Building an ADU is a great way to add extra living space to your home, but the process can be complex and confusing. At Vision ADU, we specialize in helping homeowners in Diamond Bar build beautiful and functional ADUs. We'll work with you to figure out the best design for your needs and budget, pull all the required permits, and manage the construction process from start to finish.
Type of ADUs
The following type of Accessory Dwelling Units (ADUs) are allowed in Diamond Bar, California.
 Attached ADU
An Attacched ADU connects to an existing house, typically through the construction of an addition along the home’s side or rear.
Max 1,000 sq. ft.
Detached ADU
An Attacched ADU connects to an existing house, typically through the construction of an addition along the home’s side or rear.
Max 1,200 sq. ft.
Garage Conversion
An Attacched ADU connects to an existing house, typically through the construction of an addition along the home’s side or rear.
Max 1,200 sq. ft.
Junior ADU
An Attacched ADU connects to an existing house, typically through the construction of an addition along the home’s side or rear.
Max 500 sq. ft.
Diamond Bar Property Requirements
Several rules and regulations must be followed when building an ADU in Diamond Bar. These include:
Number of ADUs Allowed
Single-family lots can build 1 attached ADU or 1 detached ADU with 1 JADU.
Multi-family lots are allowed a maxium of 2 detached ADUs.
ADU Size
850 square feet of floor area for a studio/1 bedroom.
1,000 square feet for 2 bedrooms (no more than two bedrooms are allowed)
Height Limit
The maximum height is 16 feet, measured to the top of the roof ridge, and the unit shall not exceed one story.
Number of Bedrooms Allowed
Diamond Bar allows 2 bedrooms.
Setbacks
4 feet from the property line is the minimum side and rear setbacks required for an attached or detached ADU. There are no minimum setbacks requirements for garage conversions or JADUs unless it is needed to ensure fire safety.
Parking
1 uncovered or covered parking structure is required unless the property has physical limitations. An alternative parking arrangement may be made subject to a parking waiver in such a case.
Owner Occupancy
JADUs are subject to an owner-occupancy requirement, the property owner must live on the property. All other ADUs built in Diamond Bar after January 1, 2020, but before January 1, 2025, are not subject to any owner-occupancy requirement.
Rental Guidelines
No short term rentals allowed.
Many things make Diamond Bar, California a special place to live. One of the most appealing aspects of the city is its proximity to Los Angeles. Diamond Bar is just a short drive from the hustle and bustle of the city, but it offers a more relaxed and suburban feel.
