Oasis Builders Inc.
What are the requirements to build ADU in Diamond Bar?
Building an ADU in Diamond Bar presents a valuable opportunity to increase your living space, allowing you to host family members, earn passive income, or enhance your property's resale value. To ensure the success of your ADU project, it's crucial to understand the city's regulations and assess the financial feasibility of constructing an ADU in Diamond Bar. This guide offers a comprehensive overview of Diamond Bar's ADU regulations and key financial considerations, aiding you in planning and executing your project efficiently.
ADU regulations for properties with a single-family home
How many ADUs can you build in Diamond Bar?
In Diamond Bar, you can build up to one ADU on a lot for a single-family home. This limit applies to both detached and attached ADUs from the primary building.
How large can an attached ADU be in Diamond Bar?
An attached ADU can be up to 850 square feet or 50% of the primary dwelling’s floor area, whichever is less, for a studio or one-bedroom unit. For units with two or more bedrooms, the maximum size is 1,000 square feet or 50% of the primary dwelling’s floor area, whichever is less.
However, if the primary dwelling is less than 1,600 square feet, the attached ADU can be up to 800 square feet, regardless of the number of bedrooms.
How large can a detached ADU be in Diamond Bar?
A detached ADU can be up to 850 square feet for a studio or one-bedroom unit, and up to 1,000 square feet for a unit with two or more bedrooms.
However, if a detached ADU is combined with a JADU on the same lot, the detached ADU's total floor area cannot exceed 800 square feet.
Can I build a 2-story ADU in Diamond Bar?
No. In Diamond Bar, ADUs, whether attached or detached, should be single-story structures.
Is there a minimum size for an ADU?
Yes, in Diamond Bar, an ADU can have a minimum floor area of at least 220 square feet.
Can I convert the existing space to an ADU?
Yes, existing space can be converted into an ADU in Diamond Bar.
What is the maximum height for an ADU?
For a property with a single-family home in Diamond Bar, the maximum height of an ADU can be 16 feet, measured from the ground to the top of the roof. Converted ADUs there are no height restrictions.
ADU regulations for properties with a multi-family building
How many ADUs does Diamond Bar allow for multifamily properties?
Multifamily properties in Diamond Bar can have two detached ADUs or multiple converted ADUs. If there are no detached ADUs, you can create converted ADUs in non-livable areas of existing buildings, as long as the total is not more than 25% of the units on the lot.
How large can an attached ADU for a multifamily building be in Diamond Bar?
For multifamily buildings, attached ADUs can be up to 850 square feet or 50% of the primary dwelling's floor area, whichever is smaller, for a studio or one-bedroom unit. For units with two or more bedrooms, the maximum size is 1,000 square feet or 50% of the main unit's floor area, whichever is smaller.
If the primary dwelling is less than 1,600 square feet, the attached ADU can be up to 800 square feet, regardless of the number of bedrooms.
How large can a detached ADU for a multifamily building be in Diamond Bar?
For multifamily buildings, a detached ADU can measure up to 850 square feet for a studio or one-bedroom unit and up to 1,000 square feet for a unit with two or more bedrooms.
If it’s combined with a JADU on the same property, the total floor area of the detached ADU cannot be larger than 800 square feet.
Can you stack detached ADUs on top of each other?
Diamond Bar doesn't have specific rules about stacking detached ADUs.
Can you attach two ADUs to each other?
No, you cannot attach two ADUs to each other in Diamond Bar.
Can you convert the existing space to an ADU?
Yes, converting existing space into an ADU is allowed in Diamond Bar.
What is the maximum height for an ADU on a property with a multi-family building
The height restriction for multifamily properties is the same as that for single-family houses.
What ADU types are allowed to build in Diamond Bar?
In Diamond Bar, there are various ADU options to choose from:
1. Detached ADU: A completely separate unit, standing independently from the main house.
2. Attached ADU: A newly constructed extension that is physically linked to the existing house.
3. Converted ADU: Converting existing non-livable spaces, like garages, sheds, or storage areas, into a functional living area with necessary amenities such as a kitchen and bathroom.
You have the choice to build a new ADU or repurpose an existing structure. Conversions, like turning a garage or shed into an ADU, typically bypass certain limitations such as setbacks and height restrictions, while also allowing for the possibility of expansion. However, dealing with older structures could uncover unforeseen issues that might lead to higher expenses.
ADU setbacks from the property lines and other buildings
What are the required setbacks for an ADU in Diamond Bar?
New ADUs are required to have minimum setbacks of at least 4 feet from the side and rear lot lines. The city has not specified setback regulations for corner or through lots.
What is the minimum distance the ADU must have from the existing structures?
A detached ADU should be at least 6 feet away from the primary unit. This distance rule doesn't apply to converted ADUs that don't add extra floor space to the existing building.
Are setbacks required when converting existing structures into ADU?
No setbacks are needed for converted ADUs in Diamond Bar, as long as the existing structure meets current fire and safety standards for side and rear setbacks.
Can I build an ADU in the front yard of my house in Diamond Bar?
Yes. In Diamond Bar, you can build an ADU in your front yard, provided there isn’t enough space on your property to fit a unit of at least 800 square feet elsewhere. However, zoning setback requirements should still be followed.
Design requirements for ADU
How many bedrooms can an ADU have?
ADUs in Diamond Bar can have at least one bedroom, as opposed to studio units.
Does an ADU need to have a kitchen?
Yes, ADUs in Diamond Bar need a full kitchen, unlike JADUs, which may have smaller setups.
Does an ADU require independent utility meters?
No, an ADU in Diamond Bar typically shares utility services with the primary residence and doesn't have separate metered utilities, unless it's required by specific building, fire, or electrical code provisions. If the ADU uses septic facilities permitted by the relevant authorities, written certification of approval by the local health officer should be provided.
What is the minimum ceiling height?
The minimum ceiling height for livable areas in ADUs in Diamond Bar is 7 feet, as required by the California Building Code.
Find out the maximum ADU size for your property here
The parking requirements for ADU
What is the parking requirement for an ADU in Diamond Bar?
In Diamond Bar, one additional off-street parking space is required for new attached and detached ADUs, with exceptions for proximity to public transit, historic districts, or if certain conditions apply, such as the ADU is 800 square feet or smaller.
Where can I have a parking space on my property?
In Diamond Bar, parking spaces for an ADU should be accessible from the existing driveway and can be located in setback areas or as tandem parking unless deemed unsuitable. If a garage or carport is converted for the ADU, no replacement parking is required.
How to get permits for your ADU
How long does it take to get an ADU permit in Diamond Bar?
In Diamond Bar, obtaining an ADU permit generally takes between 105 and 120 days. Once your permit drawings are complete, you or your architect can submit them for a Plan Check. It’s a good idea to meet with the planner beforehand to ensure your application is ready.
After submission and payment of fees, the city has 60 calendar days to determine whether the application is complete. If there is no response within this period, the permit is automatically approved. If corrections are required, your designer will need to revise the application and resubmit it. The application should provide sufficient details to demonstrate compliance with ADU regulations, as missing information alone is not grounds for denial. Plan check fees for ADU projects in Diamond Bar are approximately $4,029.
Does Diamond Bar require in-person submission of plans for an ADU?
No, Diamond Bar does not require you to submit plans in person. You can start the formal plan check process online through the Building Permit Application web portal. After submission, staff will review your application and send information about fees and next steps via email.
Does Diamond Bar require coastal development permits?
No, Diamond Bar doesn't require coastal development permits in any area.
When do you need a licensed professional to design an ADU in Diamond Bar?
In Diamond Bar, you will need a licensed professional to design an ADU if your project does not follow standard construction methods.
Cost, financing and market value of ADUs
How much does it cost to build an ADU in Diamond Bar?
In Diamond Bar, building an ADU costs roughly $380 per square foot. Alongside construction costs, you should also budget for permits, architect fees, and engineering fees. For instance, the total cost for a 900-square-foot ADU is around $390,000, including both soft and hard costs.
Is it profitable to build an ADU in Diamond Bar?
The economic feasibility of building an ADU in Diamond Bar depends on construction costs and the local real estate market. A 900-square-foot ADU in this area is valued at approximately $540,000. With a total construction cost of around $390,000, this results in a return on investment of about 37%.
Profitability can also be evaluated by considering potential rental income or the benefits of having family members reside on the same property.
Can you sell an ADU in Diamond Bar?
AB 1033 allows local agencies in California to set rules for selling accessory dwelling units (ADUs) and primary residences as condominiums while keeping current ADU development regulations intact.
In Diamond Bar, selling an ADU is subject to local ordinances with specific conditions. The ADU can be sold if it was constructed by a qualified nonprofit, if there is a recorded tenancy in common agreement, or if the city allows the ADU and primary home to be sold as separate condominiums.
Are ADUs rent-controlled in Diamond Bar?
No. Rent control typically applies to older buildings, those aged at least 15 years. Since ADUs are newly constructed, they are exempt from these regulations. Therefore, laws such as AB 1482, which addresses rent control, do not affect ADUs in the city.
How do I get money to build an ADU in Diamond Bar?
To obtain funds for constructing an ADU in Diamond Bar, homeowners can consider programs like the CalHFA ADU Grant Program. This program offers grants of up to $40,000, with eligibility determined by the homeowner's income, which can reach $158,000 for owner-occupied properties. The grant covers initial expenses such as site preparation, ADU design, permit acquisition, and other related costs. Homeowners retain the flexibility to choose tenants for the ADU.
Find out how much value an ADU could add to your property.
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