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California ADU Guide | Learn From Top Real Estate Lawyers

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Are you thinking of building out an ADU (accessory dwelling unit) in California to save money, make money, or increase your property value?

Read our comprehensive guide, which includes all the information you need on ADU laws California created within the last few years.

Are You a California Resident Looking to Build a Unit on Your Property? 

If you live in California and you’d like to build a unit on your property, then you’re in luck thanks to the approval of California ADUs. Find out from experienced California ADU lawyers on how to build and what to look for. 

Let’s delve deeper into the details of ADUs. 

What Are ADUs?

An accessory dwelling unit (ADU), often referred to as a granny flat, is a secondary property situated on the same lot as a single-family residence

What are ADUs used for?

When single residences are zoned, they are generally only zoned for one house on the lot. This property is typically considered an R1 which serves as the only house you can have on the lot.

This rule was always the case until California passed a law that permitted single-family residents to build secondary units on the same piece of land. 

Types of ADUs

Before you begin building, it’s necessary to identify the different ADU models

Single-Family ADU Development

Single-family “granny flats” are the most common kind in existence. You’ll often see them as a converted guest house, backyard cottages, or garage separate from the actual home. Some owners may even build their ADU as a basement unit or outward extension to the existing property.

Junior ADU Development

One of the key differences between a regular ADU and a junior accessory dwelling unit (JADU) is that the JADU must be enclosed within the primary home. 

Furthermore, JADU developments have occupancy requirements, meaning the owner of that ADU is either required to live in that granny flat or the single-family home on the lot. 

Multi-Family Lots ADU Development

Multi-family ADUs prevail for Californians who own multi-family zoned properties.  Similar to all other ADU developments, your multi-family ADU must be residentially zoned. 

Multi-family ADUs are allowed to be much larger than your typical single-family ADU development.

What are the Benefits of ADUs?

ADUs are beneficial for several reasons. Given that granny flats are additional living facilities, it provides builders the ultimate access to extra housing.

California currently faces a substantial shortage of available homes, making ADUs an excellent alternative.

There is no subsidiary land cost. Therefore the financial incentives help raise housing supply considering these flats remain on the same land as your main house.

The official ADU Handbook shares the latest benefits as ADU laws evolve. Here is additional important information, guidance, and sample materials from the California Department of Housing and Community Development

Key California ADU Laws

As 2021 becomes a thing of the past, these new California granny flat laws will determine your eligibility to build ADUs. There are two laws, in particular, you’ll want to keep an eye on as we move through 2022. 


California SB9 is a new state law signed by Governor Newsom on September 16th, 2021, granting you the potential to build fourplexes on any single-family lot in the state. This law will go into effect on January 1st, 2022. 

SB9 is a state law that pushes requirements on local governments, such as counties and cities, in California. Many believe this new bill will lead to the termination of single-family zoning. So, who will be eligible once the law goes into effect?

SB9 has two provisions with the first allowing you to subdivide any single-family property into two properties. The second provision permits you to build a second home on any single-family property. 

Subsequently, you could end up with four units across two single-family homes. This zoning law change is massive but includes a plethora of restrictions. 

The most major SB9 restriction states that before building a second unit or subdividing an existing property, the owner must sign an affidavit. This affidavit enforces that the owner intends to occupy one of the units as their primary residence for at least three years. 

Violation of this affidavit is considered perjury. This occupancy restriction often makes SB9 a vital bonus for property owners and a significant disadvantage for developers. Take a look at this comprehensive list of the other SB9 limitations:

  • U.S. census-designated urban areas and coastal zones only.
  • No historic districts or fire hazard zones.
  • Parcels must be a minimum of 1200 square feet.
  • Local agencies can require one parking spot per unit if the parcels aren’t near mass transit.
  • Only one wall of an existing single-family home is demolishable. Site redevelopment must take place. 
  • Often requires low-income housing, rent-controlled housing, and units with tenants. 


SB10 is essentially a law that states when a city decides to increase the density on any given lot, that area won’t be subject to sequel review or other regulatory obstacles. Additionally, this zoning law is centered around the local control that already exists.

Ultimately, cities will continue to upzone lots if they so choose.

The bill is less about individual property owners looking to build further on their lots and more about Californian cities opting in on this opportunity to upzone with far fewer restrictions.

How Do California ADU Laws Benefit Homeowners and Investors?

Here are some of the benefits of building an ADU with an existing residentially zoned property:

  • ADUs can be used as an additional source of income for homeowners as rental units.
  • ADUs are an affordable method of creating additional value and square footage to your property because they do not require paying for additional land, major new infrastructure to the property, or structured parking.
  • ADUs allow family members and residents to have flexible, independent living accommodations yet still be near one another while maintaining privacy.

Getting Started With an ADU in California

Now that you understand the laws and benefits of ADUs, you’ll need to see what the application process entails. Here is one of many examples to review.

Furthermore, cities don’t have permission to require the correction of zoning conditions as part of the approval process. 

Check Your Zoning and Easement Laws

Easement and zoning laws determine your flexibility when building ADUs.

Lot requirements

If you have a relatively small lot size, you might consider placing an ADU in that area. Fortunately, compact lots are still eligible for distinct granny flats. No laws prohibit owners from building on property with minimum lot size

On the contrary, the city can shoot this proposal down if you’re looking to build a very large ADU. Cities often set maximums, preventing you from putting a granny flat that is deemed too large.

Moreover, cities with no ADU ordinances have a maximum ADU size of 1,200 square feet or 50% of the lot coverage

Setback Requirements

Statewide exemptions require all ADU builders to uphold a 4-foot side and rear-yard setback on a flat no more than 800 square feet. These setback requirements may be modified by law; therefore, it is important to do your due diligence for your municipality before you begin work on your ADU. 

Do you have easements that affect your proposed ADU?

Generally, an easement can affect your ADU proposals, keeping you from building wherever the easement is located in the lot you’d like to build on. The easement essentially lessens the actual amount of property you possess.

For example, a utility easement such as power lines running through your backyard reduces how many feet of property belongs to you. This is because the space taken up by the power lines technically belongs to whatever electric company placed those power lines. 

ADU Neighbor Issues

If you want to build an ADU on your lot, could the neighbors complain about the construction? Simply put, neighbors can’t file complaints. As long as you meet all the requirements, your neighbor doesn’t have the right to an objection. 

Should you seek discretionary approval, this is something that exceeds what is permitted by right; therefore, the city can choose to ask for feedback from the neighborhood that you desire to build in.  This is the only time neighbors will be able to object.

Contact Our Office if You Need Further Help

In case any additional questions come up, give us a call at (619)-492-4198.

Do the ADU Laws Apply to Your Property?

ADU laws apply to any and every property in the state of California where the owner of that property is looking to build a granny flat.

State and Local Codes

After discussing the key ADU laws California recently implemented, there are codes to acknowledge as well.

A critical state code to note is the California Health and Safety Code (HSC), which went into effect in 2021. This code requires the counties and cities to develop a plan promoting and encouraging affordable ADU offers to low-income households.

For any local codes regarding ADUs, consult these ADU policy changes and apply the information to your city.

Are you eligible to build?

Building eligibility will depend not just on the state of California alone but also on your specific city. The most important requirements are statewide, but local governments can adopt certain restrictions.

Generally speaking, local governments cannot prevent ADUs, making eligibility easier to obtain.

What to do if you are not eligible.

If you are not initially eligible, the best course of action is to look at your local government’s specific requirements that prohibit you from building. 

This information will tell you how much space you have to build your granny flat and if you can build multiple flats on one lot.

Contact Our Office if To Learn if Specific Rules Apply to You

For more information on ADU eligibility, get in touch here

Do You Have Parking Requirements for Your ADU?

If your ADU occupies space that could be used for parking, providing available parking elsewhere is required. There may be exceptions to parking requirements in your municipality; as such, it is essential to obtain this information from the outset to avoid any additional costs or preclusion of your ADU due to lack of parking.  

Parking does not need to be covered and off-street parking is granted in setback locations. 

Get A Permit for Your ADU

Receiving your permit to build requires you to create a plan check. This plan check is for building and safety purposes. After the plan check is submitted and fully approved, the city engineer can issue a construction permit.

ADU permits are easy to acquire in a variety of ways, but there are a few things you’ll want to avoid when obtaining your permit to build:

  • Deep lots because they are often far from the road
  • Fire hazard zones
  • Creek setbacks
  • Corner and through lots

Understanding What Fees Apply to Your ADU

ADUs are not considered separate property from your home, leading to fewer fees.

The impact fee is the most notable, stating that ADUs over 750 sqft. will have fees imposed upon the ADU. In addition, permit and plan check fees will apply during the design and application process if your ADU surpasses a specific size.

Will HOAs Affect My ADU?

Fortunately, your right to build an ADU in California cannot be prevented by HOAs (homeowners associations).

ADU Building Requirements

Size Limits

Single-family properties limit you to 850 sqft., with JADUs stopping at a mere 500 sqft.

Multi-family properties reach a limit of 1,000 sqft. for newer construction flats, while conversion ADUs go up to 800 sqft.

Interior Space Requirements

Single-family and multi-family properties allow up to two bedrooms or 50% of the primary home’s floor area. This excludes JADUs, which permit just one bedroom.

Height Requirements

One story or a maximum of 16 feet is permissible in a single-family property. Multi-family properties do not possess specific height maximums or requirements. 

Electricity and Utilities

You wouldn’t pay extra utility fees as your ADU utilities and electricity will connect to your principal home. 

Cost Calculations

Utilizing a cost calculator correlated to your city or county is the most effective way to receive accurate building prices. A prefabricated California ADU is less expensive than standard flats.

Financing Your ADU

Take into account some of the best ways to finance your ADU.

What Financing Is Available?

Do I Have to Abide by Owner-Occupancy Requirements?

Owner-occupancy requirements apply based on your local government, but it’s habitually not required. On the contrary, your city could require an ADU applicant to be an owner occupant.

Frequently Asked Questions

How many ADUs can I build?

Depending on the lot, new zoning laws now permit fourplexes on a single property. 

Can HOAs prevent ADUs?

Restrictions may arise and be set on your ADU, but HOAs will not get in the way of your building desires.

Do ADUs increase property value?

Adding extra housing to your property will ultimately increase its value.

What is the maximum size of an ADU in California?

ADUs in California cannot exceed the maximum size of 1,200 sqft.

Is an ADU a tax write-off?

Adding an ADU may impact your income taxes, which can be rather complicated. It’s best to discuss the implications with a tax advisor. The rental income you receive for your ADU is taxable. 

Still, you can deduct the cost of maintenance and depreciate the cost of construction, which can often reduce or eliminate the tax increase. You may also have capital gains tax related to the increased value when you sell your property.

How much does an ADU permit cost in California?

In California, ADU permits can cost anywhere between $2,000 and $11,000, depending on location and overall design.

How close to the property line can I build an ADU in California?

As long as you remain 5 feet from the property line, you can build your ADU without objections. 

Does an ADU count as square footage?

Yes, an ADU does count as additional livable square footage to the property.  However, the value of that square footage would depend on whether it’s a detached ADU, an attached ADU, or conversion/modification of the existing space, i.e., garage conversion.  

In addition, the value of the extra square footage will depend on the type of ADU. 

How is the ADU value calculated?

Calculating the ADU value is done by multiplying the total size of the unit by the property value per square foot.

Do you need a permit for ADU in California?

Whether your ADU requires a permit will depend on several factors, including square footage, the type of addition, your municipality, the utilities and design of your ADU, and your overall build. 

For more information on ADU permit requirements, get in touch here

Do the new ADU laws make you eligible to build?

The new laws that were passed in California still grant you building eligibility with less extensive restrictions.


ADUs provide great financial incentives for affordable housing, investors, homeowners, and individuals searching for extra income. If you are looking for guidance on how to navigate building an ADU, then contact Equity Legal today.

You can schedule a free 15-minute consultation directly from our website.


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