California ADU Laws: Backyard Home Regulations

Since 2005 California has had a housing shortage of 180,000 units.

The persistent housing shortage in the state has caused prices of homes to shoot upwards out of the reach of many residents.

One alternative Californian authorities are turning to ease this pressure is the Accessory Dwelling Unit (ADU).

ADUs, also known as granny flats or backyard homes, are housing units that exist on a lot with another house. They can be detached or attached.

Since many Californians already live in ADUs, the state sought to make it easier to build more by revising the law in 2016. There have since been more changes to the law.

Here are the backyard home regulations you need to know before building or moving into an ADU.

The law supports more ADUs

It is now easier for single-family homeowners to construct different types of ADUs. This stems primarily from the fact that regulations surrounding a local government’s ability to designate areas and apply development standards support ADUs.

According to new, ever-evolving laws, ADUs on single family home, residential properties must be allowed, should they meet the minimum requirements of their state, county, city, and neighborhood jurisdiction. But building an ADU and getting it approved is not always so simple.

Backyard home regulations on space and size

California granny flat laws give local authorities power to determine the space and size allowed to permit an ADUs.

Local governments have the right to adopt requirements that reduce the restrictions on backyard homes. That is in line with the aim of ADU regulations which seek to promote their development, however can create different challenges in different jurisdictions.

An illustrative example of this is with San Jose. The area faced a continuous shortage of housing for many years.

With a fast-growing population, San Jose decided to promote ADUs as a housing opportunity, not only to expand inventory for citizens, but to provide more comfortable housing options for multigenerational families. They first created a manual to provide more information to homeowners on ADUs.

The manual was in response to their research that showed many homeowners would build an ADU if they had information to make the navigating the regulations easier.

In light of this, authorities chose to make the information easy to find to guide homeowners on the requirements and processes necessary.

In addition to this, San Jose changed some regulations to stimulate ADU development. For example, they set the minimum lot size one needed to build an ADU at 4,500 sq. ft. That meant that more homes qualified to build an ADU.

On the flip side, local authorities can also adopt more restrictive policies on ADUs.

All in all the maximum size for a granny flat is 1,200 sq.ft. or half the size of the existing residence. A detached ADU must be ten feet away from the main residence and five feet away from any property lines.

Since the local authority has the power to relax or tighten the laws, it is good to check with their offices before starting construction.

The Parking Space Question

In the past, granny flat laws demanded that for every unit, you needed a parking space. That proved to be a notable barrier for homeowners who wanted to build an ADU. Additional parking spaces cut into the spirit of the laws surrounding lot size, and also created additional expensive budget barriers..

The 2018 amendment to the law does not require parking if the ADU is within a half mile of a public transit transport stop. The law also gives local authorities the ability to develop a broader definition of what makes a public transit stop. And in some cases local governments create additional or what we’ll call adjacent laws that contradict the state regulations. That’s why so often, each property must be assessed case by case.

Part of the latest version of California ADU laws eliminate most parking concerns. Specifically, if the ADU is within one block of a car share then you are exempted from including parking space.

Such a regulation might not seem significant but in some parts of the state, this can have major implications.

Take Berkeley for example. Nearly every home is within a half-mile of some form of public transit stop.

If the law were to require parking for every ADU unit built, it would have a huge impact. Most likely, the building of granny flats would dwindle and stagnate a lot.

With the revision of parking requirements, more residents of Berkeley can now afford to build backyard homes.

Pre-Fabricated ADUs

In many more rural areas, pre-fabricated ADUs can be good options for homeowners looking to save time in construction. .

But if you are dealing with an ADU you can’t assume that you can go ahead to erect it. You still need to find out if the laws in your area support ADUs or not, and what kind of project best suits for property needs.

Californian law does allow you to use manufactured or factory assembled housing options to build ADUs. According to the government, manufactured housing is:

● Any structure that can be transported in one or more sections

● Eight body feet or wider or 40 body feet or longer when packed for transportation or erected on site

● Made on or after June 15th 1976

● 320 sq.ft. or more

● Built on a permanent chassis and designed as a single family dwelling

● 40 body feet or more long


Know what the law says about ADUs

There is a persistent housing shortage in the San Francisco Bay Area and througout all of California that has led to many people struggling to find housing. And not just for themselves, for their own families. ADUs are one way that the state can alleviate the lack of housing while keeping the costs manageable.

However, before you build an ADU, you must understand the backyard home regulations and comply with them, or find a partner that is a great fit for you and can navigate the growing complexity of accessory dwelling units

Acton ADU is ready to bring its wealth of experience and skill to your ADU project. Speak to us today if you are looking for a top-notch ADU home builder.

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