Get Started

Overview of California ADU / Granny flat laws

A new California state law took effect on January of 2017 to encourage homeowners to build accessory dwelling units, better known as Granny Flats or Inlaw studios.

In the past most counties within California discouraged homeowners from building and renting additional units on their property. Due to the lack of affordable housing throughout California and rising rental rates, California is making it easier to add a Granny flat to their home and legally rent. Of course these ADUs are also perfect for an elderly relative, caregiver, guest home or for a child still living at home. Although fees are being cut all across the state to encourage homeowners to add ADUs to their property, the process is still quite complicated.  We will try our best to help you.

What is an ADU?

Accessory Dwelling Units (ADUs) are also commonly known as: granny flats, in-law units, guest homes, backyard cottages, secondary units and more. It is a residential unit that can be added to an existing home. An ADU can be detached from the home, attached to the home or a detached garage or a conversion of a room within the home. Conversions are usually made to detached or attached garages. Each ADU is an independent unit that have their own kitchens, bathrooms and living areas.

Why would you want an ADU?

ADUs are great for rental income, grown children, inlaws, elderly parents and used as guest homes. With recent changes to the law, lack of housing and skyrocketing rental rates, ADUs are a great way to bring in additional income and increase the value to your property.

What are the current Laws for ADUs in your area?

State legislation that took effect January 1, 2017 gave California cities more flexibility to allowing homeowners to build ADUs. Three separate bills were introduced and signed by Governor Brown; SB 1069  (Wieckowski), AB 2299  (Bloom), and AB 2406  (Thurmond). Each of these land bills make it easier and more affordable for homeowners to add these units to their home. Many cities are also passing further bills to cut additional fees such as hook up fees and waiving many requirements previously required as an incentive to add more housing units to their cities.

Please find information regarding your specific city/county on our List of ADU regulations by City / County in California.

Can you add an ADU to your property?

can i add an adu

This should be the first step in determining if you can add an ADU to your existing property.  Most homes can add an ADU, but you might not have enough space for a detatched ADU, some homes don’t have a garage or any additional living areas that can converted and provide their own entrance and some homes have existing guest homes or an existing ADU.  Only 1 ADU per single family residence is allowed.

ADU Unit Explanations and Images from citylab / UCLA for the County of Los Angeles.  For a complete version of their guidebook, you can access it here.

attached and detatched granny flat

adu garage conversions

You can design and build almost any type of ADU or purchase a manufactured ADU.  Some cities may have specific design and setback guidelines.  Please find information regarding your specific city/county on our List of ADU regulations by City / County in California.

adu design samples

How many parking spaces will I need?

Depending on your county, most homes will need an additional parking space when you add an ADU. Some citys have waived this requirement and others will waive the requirement if your home is located close to public transit, is located in a historically significant district or when an ADU unit is created by a conversion of a garage or room inside the home.

You can find all the information related to your city here.

So if it looks like you can add an ADU / Granny Flat to your lot, what to do next?

Make a sketch

Before you submit your building permit application, make a sketch of your existing lot and make a copy that you will add the proposed ADU to.  You can get the basic dimensions for a manufactured ADUs here or provide a rough sketch of what you would like to build.  This will be used to determine if your plan will work.  Print a sheet of graph paper, you can get a good version here.

How much does it cost to build an ADU?

Costs can vary quite a bit from area to area.  Some other factors that will affect your costs will be your decision to convert an area within your home to an accessory dwelling unit, if you will be converting a garage, purchasing a manufactured ADU or building a custom ADU on your lot.  Then you will need to consider size and the cost of construction in your area.  Manufactured Home dealers, builders and architects can give you a rough estimate on your project.  You can find additional cost information in the Construction Section.

How can I pay for my ADU?

The most common way at this time is to self finance or borrow from a home equity line of credit / HELOC.  You can also consider a cash-out refinance or getting a private construction loan to be paid off with a refinance after construction.  More and more communities are also funding different types of financing services specifically for building ADUs in their communities.  You can find more information in our Financing Section.

How can I find out how close I am to transit?

Many homes in California are located within 1/2 mile of transit and additional parking requirements will be waived.  You can search using Google Maps to see if you are located within 1/2 mile of a bus stop or rail station.  You should also contact your local Department of Building and Safety to confirm if you need to provide additional parking for your ADU.

Can I sell my ADU?

No, you can only sell your house and your ADU together.  You may rent your ADU if desired.

Can I rent my ADU?

Yes! You can rent it to anyone or provide it for a older family member.

Must the owner live in one of the units?

In some areas like Los Angeles, a homeowner is not required to live on the property and both the existing house and ADU can be rental units.  Check with your local city / county requirements.

Can I add an ADU to a rental property?

In some areas like Los Angeles, a homeowner is not required to live on the property and both the existing house and ADU can be rental units.  Check with your local city / county requirements.

How big can I make my Granny Flat / ADU?

An ADU can’t be larger than 50% of your existing house and can’t exceed 1200SF.  Some areas might have additional requirements regarding lot sizes and percentage of areas used.  You will want to check with your local building department for that information.

Can I convert a storage container in to an ADU?

No, most cities have ordinances against storage containers on residential lots and you would have a difficult time legally converting a storage container to an ADU.

Can I buy a manufactured ADU for my lot?

Yes, all newly built and certified manufactured homes comply with the standards established under the National Manufactured Housing Construction and Safety Act of 1974 and would be considered a residential dwelling unit with independent facilities for living, sleeping, cooking and sanitation.  An ADU includes an efficiency unit (Health and Safety Code Section 17958.1) and a manufactured home (Health and Safety Code Section 18007).  Buying a manufactured ADU will speed up your construction time, lower your costs and most likely provide you with a higher quality ADU than custom construction.

Can I buy a used mobile home to use an an ADU on my lot?

No, an older mobile home, RV or travel trailer can not be used as an ADU in California.

What should I do next?

Determine your budget and financing needs, consider what type of ADU you would like on your property and construction requirements for creating an accessory dwelling unit for your property.