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What is an Attached ADU?

Updated: Feb 16, 2023

What is an Accessory Dwelling Unit?

An Accessory Dwelling Unit is essentially a second housing structure that occupies the same lot as the primary home. These structures are called many different things, from mother-in-law suites, granny flats, secondary dwelling units, and so forth. The units are equipped with a living space, kitchen, bathrooms, and can be either attached or detached from the main home. Regardless of the type of structure, such as a basement, cottage, or garage, the ADU is legally part of the same structure of the main house.

Types of Accessory Dwelling Units

They are typically classified into three main categories: interior, attached, and detached. Interior involves converting an existing space, such as an attic or basement. Most of the time utilities and appliances will be shared. Also, the structure may have a separate entrance.

So what is an Attached ADU? An Attached ADU is an add-on to the existing home structure, such as adding space above an existing garage. Typically the structure will be connected via a wall from the main house. Some share the utilities and appliances with the main home, while others have separate connections.

Detached are structures separate from the primary dwelling. They can be constructed over existing structures or built separately from the primary dwelling.

Why Would You Want an Attached ADU?

The two most common reasons for building Accessory Dwelling Units, whether attached or detached, are housing family members and rental income. Over time, the family needs change for many people. The way most houses are designed in today’s world does not reflect the changing needs of people. Maybe your parents are getting older and you need a place for them to live that is close by.

Perhaps you are looking to save money and you have a friend or family member that can occupy the space. The other common reason people build these is to supplement their income. New construction houses are increasing at 7%-8% per year, while the average income is lagging. Most existing houses have the space available to provide housing to people who otherwise could not afford it.

Pros and Cons

Accessory Dwelling Units provide a variety of benefits to communities. They help increase a community’s housing supply and are an affordable option for many low-income families. The community will also benefit from higher property taxes that will go towards schools. The most common reason they are built is for aging family members. Planning out your design allows you to make the structure ADA compliant for future needs. This gives family members peace of mind knowing their loved ones are close by and safe. Some other benefits include the following:

• Environmentally friendly

• Provide income and stability to families

• Offer flexible space for families

• Offer rental access to great neighborhoods not accessible to some previously

• Low housing cost for adult children

• Private accommodation for guests

While these benefits are great, you must also consider the cons that come with it as well. Some examples include losing space for storage, such as an attic or garage. Also, you must consider the loss of privacy you will deal with, assuming you are renting this out to a third-party. Along with this, you will also be responsible for maintaining the property, as a landlord would do. So be prepared to cover repair and maintenance expenses. Finally, you must consider the cost of construction. New construction ADU’s can cost between $60,000 to $150,000, while the average cost of a garage or basement conversion is around $30,000. This is because there is no new construction involved and you are just converting existing space. Some additional drawbacks include the following:

• Higher property taxes

• Regulatory red tape

• Greater maintenance load

• Potential for vandalism

Who Can You Trust?

Once you have made up your mind that you are ready to proceed, the next step is finding a reputable builder. That is where NEO Builders comes in. When it comes to build and ADU, these terms go hand-in-hand with NEO Builders. You can have peace of mind knowing they will walk you through every step of the process. From helping you with financing options for your attached ADU, to creating the blueprints and getting all required permits, to finally building your structure. They will also give you information on how to rent out your attached ADU structure, should you choose to do so. Check out some of their projects here.


Hopefully, the article above provided some good insight into what you can expect with owning an attached ADU. If you are ready to take the plunge, I highly suggest contacting NEO Builders for all of your needs. As mentioned before, build and ADU are two terms that are fundamentally understood by this company. If you are still asking yourself "what is an attached ADU?", you can visit their website for all of your attached ADU needs.



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