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A Guide on ADU Law in California for 2024
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A Guide on ADU Law in California for 2024

|Feb 15, 2023

The state of California has seen a huge rise in the construction and planning of ADU ever since the laws are made easier for everyone. With only a minimum space requirement for several loaning opportunities, the California ADU laws are highly supportive for homeowners; hence many people are planning to build a modern shed where they could work, play, rent out or use it as an extra room to the house. From buying a portable shed or a studio shed to constructing from scratch, it is always fun to involve yourself in a home renovation project.

But before you gather all the monetary and physical resources, you must be well aware of ADU California laws so there is no problem in the future. An important part of how to build a shed or backyard ADU depends on the ADU California laws, and in this article, we have simplified everything for you.

What is an ADU in California?

While the definition of an ADU (accessory dwelling unit) remains the same in all parts of the country, an ADU in California comes under an attached or independent residential unit built on your property. For your ADU, you must have a backyard or garden space where the extra unit can be built. The unit can be designed for personal use, as a granny shed, or as a place to rent out for some passive income. The ADU interior and exterior have to abide by the ADU laws set by the state of California.

What is an ADU in California?

What Are ADU Laws in California?

California is doing its best to allow the building of ADU and the purchase of prefabricated ADU units for all of its residents, which is why they have provided complete transparency regarding ADU laws in California. Reading these laws will help you build the right structure which is safe, fool-proof, and cannot be rejected by lawmakers in the future. Below are some must-know ADU laws in California.

Minimum Size

When constructing multiple ADU, each ADU must be a minimum of 1200 square feet in measurement. This ensures that each lot follows the minimum required space for a livable size. Also, another part of the law states that the ADU cannot be rented for less than 30 days.

What Are ADU Laws in California?

ADU Height

For an attached ADU to your primary structure, the ADU height must be 25 feet or the same height allowed by your zone. This is to form a uniform-looking structure throughout the zone. However, the city must permit you to build up to 18 feet if you do so on land where you already have or want to develop a multi-family, multi-story home.

Approval of New Build Proposal

Under senate bill 9 for ADU, all the construction proposals need to be approved by the cities and counties in the area. This is to ensure the construction meets the standards of size, height, and laws set by the state. This will prevent any permission issues and issues that normally arise during the rental of your property.

New Builds Must Not Change Occupied Housing

According to the Senate Bill, a newly built California ADU cannot alter or destroy affordable or rent-controlled housing that has been occupied during the previous three years. Additionally, no land part of a historic district or designated as a historic landmark may be used for new construction.

Intended Use

Intended Use

It is to highlight in the law that the new building cannot be used for commercial purposes but only intended to be used for residential purposes. The new units cannot be termed for short-term rentals.

This will be ensured by the property owners signing an affidavit stating that the housing units constructed must be used as a primary residence by the homeowner (or one of them at least). The owners should be residents for at least three years from the date they have decided to split up their property for other purposes. This ensures that the ADU construction happening is intended for long-term use.


Allowing the construction of a structure will require loans or any financing options. This means you will be worried about being restricted from getting a loan because of your low income. However, as per the latest ADU laws, even low to moderate-income earners can get on board with the ADU constriction. This also means that there will be several financing options for building an ADU.



An ADU, to be classified safe for living or rental purposes, must have certain amenities or facilities. Without that, you cannot rent out an ADU, no matter how spacious or expensive it is planned. The first and foremost rule is that an ADU must have a separate entrance for privacy reasons. Secondly, ADU must have a minimum of ¾ bath with a toilet, shower, and sink. Thirdly, ADU must include cooking, eating, sleeping, and living provisions hence having kitchen or other safety standards such as a fire alarm or fire sprinklers. Having insulation in the structure is also a requirement for an ADU.

Why Should You Have an ADU?

An ADU is a popular concept, especially in California, because of its numerous benefits and the state's improvement of living standards. Here are some reasons why you should invest in an ADU in California.

Increased Home Value

This is the greatest benefit of a backyard ADU. An ADU is an extra space on your property. It improves the livability of your property and provides additional space with all the facilities. Hence an ADU increases the home value significantly.

Why Should You Have an ADU?

Source of Income

An extra and reliable source of income, an ADU provides extra money to the homeowners in the form of rent which is reliable and a great return on investment.

Suitable for Extended Families

Whether it's your grandparents who prefer to live in their own space or your relatives who need their privacy but don't want to be far, an ADU is a great solution. It is also a smart idea for a teen who has recently turned 18 and is planning to live independently. An ADU will provide the right level of proximity and privacy to the person.

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