What Is an ADU and Why Should You Build One?

The average cost for a house in California has now reached $600,000 and $996,000 in the Bay Area.

This shocking statistic is the reason behind the devastating housing crisis in the state of California, and as a result, many residents are looking for alternative forms of housing.

An ADU in California has become a popular, affordable alternative for those looking to make their living in California without breaking the bank for housing.

But what is an ADU? Why are these dwellings so appealing as alternatives to traditional homes? Why should you consider building an ADU of your own?

Let’s review a few reasons why an ADU may be the property answer you’re looking for, and how one of these dwellings can benefit you and your family.

What is an ADU?

What is an ADU? First, let’s start with the basics.

An ADU is an accessory dwelling unit. Simply, it’s an addition to a permanent housing situation, whether attached to the house or standing independently.

While ADU may not be a familiar term to you, you’ve probably heard of some of the other names it goes by:

  • Granny flat
  • In-law suite
  • Accessory apartment
  • Guest unit/apartment
  • Carriage house
  • Family unit

An ADU is a self-contained living unit that is sometimes attached to an already-built home or stands independently on the home’s property.

Tiny houses are a great example of an independently-standing ADU, but not all tiny houses actually fall into the category of ADU. To qualify as an ADU, the housing unit must stand on its own foundation and have its own sewer soliton and utility hookups.

There are a few different categories for ADUs:


This is an ADU that’s completely detached from a home, such as a tiny house, a small cottage, or other similar, free-standing building that’s completely livable. The detached ADU has its own utility lines and sewer line..


An attached ADU is, you guessed it, attached to the primary house, usually as an addition or converted garag.eInternal

An internal ADU is one within the permanent home. Internal ADUs are usually complicated to build according to codes, and typically share utilities with the main home, as well as walls that need to be fire rated and modified.

An internal ADU typically occurs as a basement apartment or attic that’s been successfully converted and isolated from the main house.

Garage Conversion

A garage conversion ADU is a detached or attached ADU that’s been converted to a livable space. The detached space is usually a garage that’s been modified and fitted with utility attachments.

An ADU, no matter what type it is, is considered part of the property, and cannot be sold separately. Unlike a mobile home or a tiny house, an ADU is built on its own foundation, so it can’t be picked up and moved. The ADU stays with the house or on the property, even after that property is sold.

Why Should You Build an ADU?

Deciding to build an ADU isn’t the only hurdle you need to cross.

There are plenty of zoning ordinances, building codes, and permit processes to go through before building can even start.

So why should you build one? What makes these additions so beneficial?

Guest House

Do you host a lot of family get-togethers? How about parties? Is your house the hub for social gatherings and great evenings spent with friends and family?

If you answered yes to any of these questions, then an ADU may be worth the time and effort.

An ADU, whether it’s attached, detached, or internal, makes a great guest house. With the right planning, you can even plan out an ADU with two or more bedrooms, so you can host a few extra people outside of your home.

And with the hustle and bustle of the holidays, an ADU suite is a great space to give your in-laws some privacy, as well as a break for yourself.

Home Office

In this day and age, working from home is more normal than ever. With social distancing and office rental costs on the increase, why not build an office in your backyard?

Struggling with working from home with family members around is very common. They need to continue living their normal lives without having to worry about interrupting a conference call and you need a quiet and secluded area! An ADU provides the perfect solution for you to complete your work.


It goes without saying that an ADU is a great rental opportunity. For young adults looking to get on their feet or even older adults going through life changes, an ADU is a private suite they can live in without disturbing your family and vice versa.

Renting your ADU is a wonderful opportunity for your new tenants, and it gives you the chance to learn how to be a landlord. There are plenty of training opportunities available to help you handle the responsibilities of becoming a landlord, and the extra income doesn’t hurt.

However, renting comes with its own set of problems. From bad tenants to problems with utilities, becoming a landlord can be tiresome. It takes a lot of gumption to pursue renting a space, so ensure you are prepared to handle all the problems that may pop up.

Family Space

One of the most common uses for an ADU is housing an aging relative or caring for someone in your family that needs a little extra help, without forcing them to give up their independence.

An ADU gives your family peace of mind in knowing that their loved one is a short distance away, and allows your family member to rely on care and assistance that they may not normally have without sacrificing their freedom.

Before You Build, Know the Law

Now that you can confidently answer the question of what is an ADU, it’s important to consider the zoning laws for building an ADU on your property. There also may be additional laws that go along with renting out the space, so it’s critical that you research and read up on these laws and regulations before you commit to building an ADU.

Still considering an ADU? We have plenty of design options and ideas to fit your needs and create a beautiful space on your property.

Our experts have years of experience in constructing ADUs and can help you navigate the world of zoning laws and building codes. With our expert guidance, we’ll get you fit with an ADU in no time. Contact us today.

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