ADU requirements - Glendale, California


- ADU meaning: What is ADU

- ADU’s difference from other living facilities

- ADU types

- Which type is right for you

- ADU benefits & disadvantages

- ADU regulations & zoning compliance in California

- Steps to building ADU in California

- Solar requirements for ADU & Title 24

- Why is Title 24 important

- ADU permits & builds in California statistics

- Title 24 exemptions

- ADUs built in California statistics

- Local ADU approvals

- ADU construction costs

- ADU rental prices

- Final notes

What is ADU?

Definition: An ADU, which stands for Accessory Dwelling Unit, is a smaller, independent residential dwelling unit locatedon the same lot as a single-family home. ADU is a commonly used term across the country. ADUs are also sometimes referred to as granny flats, in-law suites, mother-in-law unit, secondary dwelling units, carriage house or secondary suites.

Benefits of an ADU

ADU’s key difference: An ADU usually has its own entrance,living space & kitchen. While these units cannot be purchased or sold individually, they offer flexibilityfor generating rental income or accommodating family members. Imagine anelderly relative living comfortably in a smaller unit, saving them the need tomove to an assisted living facility.


Examples: Common examples of an ADU include attached apartments, converted garages, or stand-alone backyard cottages.

Types of ADU

There are several types of ADUs to consider based on the needs and budget. Although there are many varieties of ADUs, which sometimes are hard to categorize,we single out five main ADU types: detached, attached, interior, garage apartment orabove garage ADU.

Single family residential ADU

Which type of ADU is right for you?

The best type of ADU for you will depend on your needs and budget. Detached ADUs offer the most privacy and independence, but they are also the most expensive to build. Attached ADUs are less expensive to build than detached ADUs, but they offer less privacy and independence. Interior ADUs are the least expensive to build, but they may not be suitable for everyone, as theycan feel cramped and lack privacy. Garage apartments and above garage ADUs are a good compromise between cost and privacy.

- Increased property value: Addinga permitted ADU can significantly enhance the market value of your home.

- Rental income potential: Generate passive income byrenting out the ADU to tenants.

- Multi-generational living: Provide comfortable accommodations for aging parents, adult children, or extended family.

- Home office space: Create a dedicated workspace without sacrificing living space in the main house.

- Guest quarters: Offer convenient and private lodging for visitors.

Disadvantages of an ADU

- Permanent occupancy of space that otherwise could’ve been used for as a storage space or a garage.

- Additional costs for ADU maintenance.

- Additional property taxes and utilities will add to monthly expenses.

ADU Regulations

Before pursuing an ADU project, consult your local planning department to obtaindetailed information on:

- Permitted size and location.

- Constructionrequirements and approvals.

- Occupancylimitations and rental restrictions.


It is crucial to note that zoning ordinances governing ADUs vary significantly by jurisdiction.

A California law (AB 2299) makes it easier for homeowners to construct these small residences to address the state’s housing shortage. Building an ADU requires a lot of knowledge and can be costly. There are specific requirements and standards for the construction of an ADU.

Steps to Build Your ADU

Familiarizeyourself with ADU rules, prepare drawings and consult local planning/zoningdepartment to screen your project concept for Zoning Code compliance.


Review the ADU rules& regulations. ADUrules apply based on project type: Projects are divided to Single FamilyResidential ProjectsandMulti-Family Residential Projects.

Single dwelling unit on property, hence single-family residential dwelling units are governed by Glendale Municipal Code Section 30.34.80.Requirements for single family residential ADUs are specified for built-in & detached ADUs.

Built-in ADUs

Single family residential ADUis built within existing legally permitted space within the main house and is called Junior ADU. Itsallowed to occupy maximum 500 square feet space.


The maximum height allowed for an attached ADU is 25 feet.

The maximum height allowed for a detached ADU is 16 feet.

Multi-Family Residential

Accessory dwelling units on properties with more than one dwelling unit (“multi-family residential”) are governed by Glendale Municipal Code Section 30.34.80.

On multi-family properties, either one of two types of Accessory Dwelling Units can be constructed, but not both. The first type is conversion of existing non-livable area and the second type is detached new construction.


Prepare architectural drawings (site plan, floor plan, elevations, roof plan, and sections), and a photo survey of the site and existing buildings.


Go to the Glendale Permits Site. Apply and obtain approval for the appropriate Planning application (“Accessory Dwelling Unit –Planning Clearance for Building Submittal" or "Junior Accessory Dwelling Unit –Planning Clearance for Building Submittal")



After receiving Planning clearance, note the Approved Plan Number and download the stamped drawings, and provide them when applying for a building permit.

See below links to building permit applications for ADUs. An application must be submitted for each proposed ADU. If the project includes work other than an ADU, additional building permits may be required. See instructions at

Building Combination(Single Family) - Accessory Dwelling Unit (ADU)

Building (Multi-Familyor Condominium) - New Accessory Dwelling Unit (ADU)

Building (Commercial,Commercial and Mixed Use) - Accessory Dwelling Unit (ADU)


Planning & Zoning Appointment Request

After research, ADU drawings& pre-screening you can additionally schedule an in-person appointment to clarify any questions or concerns you have.

Alternatively, you can consult Solar G for consulting as the company has along time experience implementing ADUs locally in Glendale, CA, and will provide prompt consultations.


Title 24

Title 24 of the California Energy Code sets standards for energy efficiency in new buildings, to reduce energy usage and carbon emissions. The energy code is updated every three years. The most recent changes having taken effect on January 1, 2023.

Title 24 is a set of regulations that mandate new Accessory Dwelling Units (ADUs) in California to have solar panels.          


Title 24 formally known as California Building Standards Code, Part 6 is essentially California's green building code, encompassing various aspects like:

  • Energy efficiency: This is the core focus, mandating measures for insulation, lighting, appliances, HVAC systems, and more to minimize energy consumption.
  • Renewable energy: Solar panels, wind turbines, and other renewable energy sources are encouraged.
  • Construction materials: Sustainable and recycled materials are preferred, minimizing environmental impact.

Why Title 24 is important?

Several key reasons make Title 24 crucial for California:

  • Energy savings: Reduced energy use benefits individuals by lowering utility bills and the state by lessening dependence on fossil fuels and power grid strain.
  • Environmental protection: By promoting energy efficiency and sustainable practices, Title 24 helps combat climate change and protects the environment.
  • Economic benefits: The code stimulates innovation in energy-efficient technologies and construction practices, creating jobs and fostering a green economy.
  • Health and safety: Improved building envelope, ventilation, and air quality standards enhance occupant comfort and health.

Overall, Title 24 plays a vital role in making California a leader in energy efficiency and sustainability, benefiting the environment, economy, and residents.


You need to apply for a solar photovoltaic permit in the scope of your ADU’s necessary permits. Note* all Solar Photovoltaic (PV) permits need Power Clerk approval before applying.

To apply for solar photovoltaic permit follow the steps for solar Photovoltaic mandated by Glendale municipality to obtain the selected permit:

Step 1. Read about the program 

Guide For Applying For PV Interconnection And NEM For Under 15KW CEC-AC Residential Systems or visit to apply.



All applicants need to provide the property owner's information (not the tenant or business) at the time of the application submittal. If the applicant is not the owner, the applicant will need to obtain the owner's Glendale Permits portal account email, which will be used to search and add the owner's contact during the application submission process.


Step 3. APPLY 

After and only if the above step is completed. Note that an incomplete permit application will be voided.

ADU Permits Issued In California

According to data from California ADU project (project by UC Berkeley’s Center for Community Innovation), the most ADU permitted in California are issued for Los Angeles County,  followed by San Diego, Orange & Santa Clara.

California's-commitment to sustainability extends to its building regulations, mandating solar photovoltaic (PV) systems for most new construction, including ADUs. This mandate, outlined in Title 24 of the California Building Energy Efficiency Standards (Title 24, Part 6), seeks to minimize energy consumption and promote renewable energy utilization.

However, crucial Title 24 exemptions exist for specific ADU projects within the Greater San Diego region:

  • Small ADUs: Units with a     footprint under 620 square feet may be exempt from the solar requirement, contingent upon their location within designated climate     zones.
  • Conversion and     Addition Projects: ADUs constructed by repurposing     existing structures or adding onto existing dwellings are entirely     exempt from the solar mandate.

For ADUs exceeding 1,125 square feet, regardless of their climate zone, solar panels become mandatory unless they fall under the conversion or addition pathways, which exempt them from the requirement.

Consulting with relevant authorities and qualified professionals is essential to determine the specific solar requirements applicable to your individual ADU project in Greater San Diego. They can guide you through the exemption criteria and navigate the Title 24 regulations to ensure compliance. Check with Solar G to find out if your ADU is exempt of Title 24 requirements.

ADU Built In California


In process of complying with all the ADU requirements, including solar not all the permitted ADUs end up being built.

Consider seeking guidance from architects, designers, or contractors experienced in ADU construction to ensure compliance with regulations and optimize your project's design and functionality and building timelines.


  • Overall, 92% of ADUs are built on parcels zoned for single-family residential, but about 2% are being built on lots with duplexes, triplexes, or fourplexes, suggesting that the move to build missing middle” housing has already begun.
  • The majority of new ADUs (53%) in California are detached units.



  • A positive trend is emerging, with various jurisdictions implementing best practices to remove barriers to ADU     construction. Examples include offering pre-designed plans, forging partnerships for homeowner financing, incentivizing construction through bonus programs, and lowering financial burdens through fee reductions and     waivers. These initiatives can significantly improve the accessibility and affordability of ADU development.
  • An overwhelming majority, approximately 86%, of both the general public and elected officials express support for state-level ADU legislation. This signifies a broad consensus on the value of ADUs in addressing housing needs.
  • Despite progress, obtaining an ADU permit remains a challenge for many homeowners, with 50% reporting difficulties. The key hurdles encountered involve navigating the local approval process, addressing design limitations, and managing construction costs. These issues require further attention to fully unlock the potential of ADUs.
  • The State Legislature has actively addressed barriers related to local approvals. Key measures include establishing a 60-day timeframe for processing applications, mandating objective design standards, and limiting overly restrictive land-use regulations on ADU projects. These interventions aim to expedite approvals and create a more predictable environment for ADU development.



Construction costs  

According to UC Berkeley Center for Community Innovation research in a 2020 ADU owner survey, was found that the median statewide construction cost of an ADU is $150,000, or $250/square foot.

Per square foot cost variation of the ADUs is based on the

- unit type,

- number of bedrooms,

- type of financing used to construct these ADUs, and

- income of the property owner.

ADUs in the San Francisco Bay Area region are the most expensive to     build, with a median construction cost of $177,500 ($329/sf). In the     Central Coast region the median construction cost is $140,000 ($223/sf),     followed by $130,000 ($200/sf) in Orange and San Diego Counties, and     $100,000 ($197/sf) in Los Angeles County.


Rental prices 

  • The median rental price of an ADU in California is $2,000, ranging from $1,925 in the Central Coast region to $2,200 in the San Francisco Bay     Area
  • The overall affordability of ADUs varies by region. The median rental price of an ADU is affordable (less than 30% of household income) to the median household of two people in the San Francisco Bay     Area and the Central Coast regions. (source Berkeley Center for Community Innovation research). 

Final Notes

- Title 24 & solar requirements for ADU are updated regularly, so it's important to consult the latest version when planning an ADU project.

- Local jurisdictions may have additional requirements beyond Title 24.

- If you're considering building an ADU, recommended to consult with a qualified designer or builder familiar with Title24 requirements.



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