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ADU stands for “Accessory Dwelling Unit” (also were more commonly known as “in-law units”). Much like a guesthouse, they are independent units on a property where people may reside.


California recently passed laws facilitating the construction and permitting of ADUs in order to increase affordable housing availability for renters. A Garage is often an ideal space to convert to an ADU (called a Garage Conversion).

Homeowners and property owners  can receive increased income by renting out their former garage or transforming a parking space into an ADU.  Thus providing additional housing for students, young families or even tourists.



Cal-ADU has built a strong reputation as a dependable, reliable source in construction and retrofitting for over 35 years. We are local and know the rules and regulations to get the job done right the first time. We are part of the parent company Cal-Quake.To find out more about Cal-Quake click here.



If you own property with multi-units or are a homeowner there are many different types of ADUs. ADUs can be attached or detached from the existing home or structure and are

located within the current property lines.


We've put together a list of different types of ADUs for you to review to find the one that might be right for you.

Multi-Family ADU

JADU / Junior ADU

New ADU Law for Multi Family Buildings Launched in Jan 2020

First time, the new ADU laws launched in January 2020 allow units to be added to your existing multifamily buildings. All Cities in California must permit these types of units in multifamily buildings without applying any local development standards:

New units can be added within the existing non-living space of a building (e.g., storage rooms, basements, or garages). At least one unit and up to ¼ of the existing unit count may be created this way.

Two new homes can be build on the same lot as the multifamily building but detached from it, with 4-foot side and rear setbacks and a 16-foot maximum height.

To see an example of a multi-family ADU

click here.

A Junior ADU (or JADU) is a new category of dwelling units created by the State of California. The main difference is that a JADU is not required to have a dedicated bathroom.

Home Conversions

A converted area of the primary home,

with its own kitchen and bathroom. 

Home Addition

A unit that shares at least one wall with the primary home.

New Detached ADU

A new independent structure, separated from the primary home and often placed in the backyard.

Garage Addition​

A new unit that shares at least one wall with the garage. Units can be built above the garage.  



Homeowners and property owners build ADUs for various reasons, including:

To generate rental income

To increase a property’s resale value and home equity 

To create private living spaces for extended family or elderly parents

ADUs benefit communities by adding more housing units while maintaining the character of a neighborhood.

ADUs are more affordable to build than other types of housing, such as single-family homes, because they do not require buying new land.

Home Deck



A quick phone call is all it takes to start. One of our associate will schedules a consultation with you to fully understand your needs.


Once we understand your needs, we deliver plans and structural engineering drawings for your project. We have quick turnaround time, with the option to track your project in real-time


We are a complete one-stop shop to build the ADU of your dreams. We will create a set of drawings, get the required permits and everything else needed including the build. We make the process easy.



Since 2017, California State lawmakers have passed multiple bills to make it easier for homeowners to build ADUs. Five bills made effective on January 1, 2020 have significantly streamlined the ADU construction and approval process. These bills and their key provisions include: AB 68 and AB 881: ​Below is an abbreviated listing, but for the complete information please click here.

Require permits for ADUs and Junior ADUs (JADU) to be approved or denied within 60 days, rather than the 120 days allotted by previous law​

A junior ADU (JADU) is an ADU of no more than 500 square feet. A JADU must be within a proposed or existing single-family home or accessory structure, such as a garage. Unlike ADUs, JADUs may share a bathroom with the single-family home and must only meet “efficiency kitchen” requirements.

Prohibit application of development standards that limit size (including floor area ratio, open space, and minimum lot size) if it prohibits the construction of at least an 800 square foot ADU that meets other criteria

Limit local discretion in establishing minimum and maximum unit size requirements

Allow for up to one ADU and one JADU on any residential property

​Allow for multiple ADUs within an existing multi-family dwelling or up to two detached ADUs on a multi-family property

Remove parking replacement requirements when an ADU results in the demolition or conversion of existing parking SB 13: 

Allows an ADU to be built in the same location and physical dimensions as an existing accessory building that is demolished to provide an ADU, along with an 150 square feet addition, if provided for ingress/egress  

Prohibits owner-occupancy requirements until 2025

Eliminates impact fees for ADUs under 750 square feet and requires fees to be proportional to the square footage of the primary residence AB 670 and AB 671:

Prevent homeowners’ associations from barring ADU construction on single-family properties or imposing reasonable restrictions

Require local housing agencies to incentivize and promote the construction of ADUs that can be offered at affordable rental rates to very low, low-, or moderate-income households



Check Development Standards to Ensure Your Property Is Eligible for an ADU

Before you design your ADU, make sure that your lot is eligible in accordance with local development standards.

Find Out If You Need Additional Parking

Parking requirements for ADUs are different for each city in California. Check with your authority having jurisdiction to be certain.

Plan Site Access to Your ADU

Access is an important factor to consider for several reasons like safety and access for your tenant to the street.

Consider Privacy

How you integrate privacy into the layout of the ADU depends on the future occupant. For example a family member might not need the privacy that a tenant would.

Understand Your Site Conditions

Is your backyard flat or sloped? Does rainwater pool in parts of it? Is the soil undisturbed or has the backyard been filled in the past?

Determine If You Can Tap Into Existing Utility Connections 

ADU’s plumbing fixtures may tie into the existing sewer lateral, while septic tank connections, if allowed in your jurisdiction, need approval from the Health Department.

Verify Your Design Guidelines

The design guidelines for ADUs vary between cities and counties. Yet, common requirements do exist, and your ADU’s architectural design will be based in part on the California Residential Code

Title 24 Energy Report and CALGreen Code - Make Sure You’re Compliant 

California’s Building Energy Efficiency Standards, better known as Title 24, view ADUs as new dwellings.

Know Which Fire Regulations Apply

Check with your building department whether sprinklers are mandatory in your new ADU. Typically, all newly-built units do, but the new ADU statute provides a reprieve from this requirement.

Think About Saving Space

Space is an obvious concern for ADU dwellers, it's important to use it in the most effective way when considering storage and finishings.

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