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Claremont ADU Resources

Updated: Feb 20

What is an ADU?

An Accessory Dwelling Unit (ADU)—also known as a granny flat, backyard home, or garage conversion—is a secondary residential unit with a kitchen and bathroom that is an accessory to the primary home. 

Diagram showing different types of California ADU's
Types of California ADUs

What is an JADU?

Junior Accessory Dwelling Units (JADUs) are allowed to be created within the walls of a proposed or existing single-family residence andshall contain no more than 500 square feet. They may share central systems, contain a basic kitchen utilizing small plug-in appliances, may share a bathroom with the primary dwelling, all to reduce development costs. 

Reasons to Consider an ADU

People are beginning to think differently about their living space, and the demand for housing is higher than ever. In the last two years California has passed several new ADU laws which make building an ADU on your property easier than ever before. 


There are a number of advantages of building an ADU:

  • Source of Income for Homeowners

  • Increasing the Value and Desirability of your Home

  • Increasing the Availability of Affordable Housing

  • Making an Impact on California's Housing Shortage

What do I need to get started building an ADU in the City of Claremont?

Follow these steps to get started on your own ADU project.



Design is an important aspect of ADU planning, as Claremont requires they must duplicate the appearance of the main house.

Claremont has architectural guidelines which apply to ADUs. The style of your unit needs to be compatible with your existing property. Projects should be of the same style, materials, colors, and quality as used for the primary dwelling unit, although a proposed higher quality material is allowed.

Check out some free ADU floor plans from other California cities by clicking the link below. Please note these are NOT approved for Claremont, and are for informational purposes to help get you started thinking about design.



You must submit construction plans in order to obtain a building permit. Required plans include:






There are many ways to finance your ADU. Of course, credit scores, existing debt, and your existing equity will impact your options. You will also be assessed regarding the amount of value your ADU adds to your property value, based on comparable sales in your area.

Before you approach a lending institution, is a good idea to have an estimate of the costs, a realistic timeline, and the basic information on contracting services you intend to you.

Factors such as home equity, assets, and income will also impact your options for financing your project. Present market analysis suggests that larger ADUs (about 1,200 s.f.) have an average construction cost of $225,000 in LA County. Smaller ADUs (500 s.f.) average about $110,000 to construct. In Claremont, prices range from about $50,000 to $200,000 depending on size and design. Below are examples of the total cost of recent ADU projects built in Claremont:

Home Equity Loans & HELOC

Cash-Out Refinancing

Savings Account

Construction Loan

Personal Line of Credit

Investments / Retirement Accounts

Source:    City of Los Angeles, The Los Angeles County Development Authority (LACDA)



Before you start building, you will need a building permit and other approvals from the city of Claremont. The city will need detailed plans of your ADU project that must be drawn to scale. The city needs to determine if your project conforms to local zoning regulations, and needs to make sure that the design is appropriate, safe, and up to code.

Here's what Claremont requires for their ADU permit application:

  • Site plan showing all existing and proposed structures, parking (if required), and existing mature trees

  • Floor plan of proposed ADU, and existing structure, if project is an ADU conversion

  • Elevation plans

  • Specifications/cut sheets for all roof materials, windows, exterior doors, and exterior fixtures.

  • Photos of primary residence

  • Preliminary Title Report

  • Statement describing intended occupant (i.e., renter, family member) & estimated monthly rent

  • Landscape Plan for the area adjacent to ADU, if applicable


Ready to get started? Click below for the city’s ADU Permit:



As you go through the process to obtain your building permit, there are several fees required by the city of Claremont.

  • Plan check fee is about 1% of total valuation

  • Building fee is about 3% of total valuation

  • School fees, if project is over 500 sq. ft. (paid directly to school district)

  • Parkland fee if ADU is over 799 sq. ft.: $1,100

  • Planning Department charges development review fee for the initial ADU application of $918

  • Grading permit: $277 - $8,000, depending on the scope of the project

  • Sewer impact fees are assessed proportionally, based on the square footage of the ADU



Select a contractor by soliciting multiple bids. Always be sure to choose a licensed contractor. ADU construction costs typically range from $50,000 to $175,000. 

Be prepared: there might be some unforeseen complications related to construction, that could cost extra. These common issues include:
  • Building a proper foundation, which can happen with older garages that are built on a concrete slab

  • Reinforcing insufficient framing to give the dwelling stability

  • Extra piping and digging to appropriately connect your new kitchen sink, toilet and/or shower to the sewer system


Frequently Asked Questions

I have a vacant property or a property with a commercial use. Can I build an ADU?
ADUs are accessory to proposed or existing homes. You can apply to build an ADU at the same time or after a home is constructed on your property, but you cannot build an ADU as a stand-alone project on a vacant lot or as part of a commercial building.
Can I rent my ADU?
Can I use my ADU for short-term rentals?
Can I convert my garage to an ADU?
Will building an ADU increase my property taxes?
Are there any owner-occupancy requirements for ADUs?
What is Claremont's ADU ordinance


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