What Does ADU Mean: A Guide to Accessory Dwelling Units

Last Updated on June 27, 2024 by support

Learn More About Finding The Right ADU For You

White ADU with green doors

With property prices soaring to newer heights every year, more people are exploring options that will allow them to share existing living spaces. Accessory dwelling units (ADUs) are one of the top choices.

In this ADU meaning guide, you’ll learn more about these units and their pros and cons.

What Is an ADU?

An accessory dwelling unit is a supporting housing structure on the same lot as a standard single-family home. Other names for ADUs include the in-law flat, granny flat, backyard cottage, and carriage house.

ADUs come in different forms. However, it’s not a full secondary unit if it doesn’t provide complete living facilities independent of the main house. Therefore, a standard ADU must include a kitchen, dining room, bedroom, and bathroom.

The Different Types of Accessory Dwelling Units

Garage converted to ADU

There are five main types of accessory dwelling units. They include the following:

  1. Detached new construction ADUs. These accessory dwelling units stand alone. They are completely separate from the main house, giving users more privacy.
  2. Attached ADUs. The attached ADUs are an addition extending from the existing main residence. They are ideal when there isn’t enough space for a fully detached unit.
  3. Above-garage ADUs. These secondary units occupy the space above a garage.
  4. Garage conversion ADUs. These accessory dwellings take over the garage space instead of just the upper part like the above-garage units. Homeowners may elect to go with a detached or attached design. 
  5. Basement conversion ADU. These ADUs convert the basement into a complete living space, typically with a designated entrance. 

Along with these types come ADU design ideas to help them fit your style.

Before settling on the type of ADU to construct for your home, you need to evaluate the local rules in your area. For example, in Tucson, AZ, your ADU cannot be bigger than 10% of the lot size (a maximum of 1,000 square feet). The maximum height must also match the size of the primary structure if you live in a home with two floors.

In our experience, we’ve noticed that queries around “ADU meaning” stem from confusion about the property dimensions.

 The Advantages of ADUs or Backyard Cottages

Light blue ADU

ADUs or backyard cottages are beneficial in the following ways:

  • They are income-generating assets. A fully-fitted ADU is an additional source of income for homeowners who rent them out. The extra income can go toward paying off the mortgage on the lot.
  • They increase the population of an area. ADUs increase the number of occupants on a lot. In a sparsely populated neighborhood with no more empty lots to build on, ADUs are a great way to bring more residents to the area.
  • They keep families closer. Senior citizens can choose to move into ADUs to stay close to their loved ones and caregivers. Younger families may decide to live in an ADU at home until they qualify for a separate mortgage.
  • They are great for downsizing. Senior citizens can elect to move to an ADU and rent out the primary unit.
  • They are a perfect option for a home office. With remote work more popular than ever, ADUs give you a proper office away from the main living areas.

The Disadvantages of Accessory Dwelling Units

ADUs are not without their disadvantages. Some of them include the following:

  • They require as much attention as a traditional single-family home. An ADU is essentially another home, so you must pay attention to permits, building codes, and more.
  • Building an ADU is expensive. Sometimes, it costs as much as a brand-new traditional home in other places. You’ll also have to pay higher property taxes and higher utility bills.
  • ADUs require maintenance. If you use the property for rentals, you must keep it in shape.
  • ADUs take up usable square footage. Building a detached or attached ADU will make your outdoor living space much smaller overall.

Frequently Asked Questions

Guest house ADU

Do I Need an Accessory Dwelling Unit?

The decision to build an ADU comes down to your personal needs.

Do you have a genuine desire to give your family a little extra room? Do you want to move your loved ones closer? Will a little more income as a landlord move the needle for your financial situation?

After answering these questions, the next step is to research the regulations surrounding ADUs in your area to avoid breaking any codes.

How Much Does Building an ADU Cost?

The cost of building an ADU varies as widely as the cost of building a traditional home. Detached units will cost more than those attached to the existing structure. Additionally, your choice of furnishings, fittings, materials, and the number of contractors required for the project will significantly influence the final cost.

You can expect to spend between $3,500 and $300,000 for an ADU. As a result, they are not always the affordable housing units many say they are.

Will an ADU Improve the Value of Your Home?

ADUs can increase the value of a property. However, it isn’t easy to quantify the value they can bring. Property owners only find out the value of the ADU when it’s time to sell the property.

Away from the financial aspects, you should consider other ways an ADU can bring value to your home. For example, an elderly family member living in an ADU may enjoy the feeling of living next to loved ones instead of in an assisted living facility. 

Can I Build an ADU as a DIY Project?

Unless you are a qualified professional in the several contractor areas required to complete a home, you can’t build an ADU as a DIY project.

Apart from erecting the structure, you need plumbing, heating and cooling, electricity, interior decoration, and more. Taking on projects in these areas without the qualification will lead to legal troubles.

Find the Perfect ADU For Your Home

We hope our “ADU meaning” article cleared up all your questions about these secondary units. Are you convinced you need one? Frei Remodeling & Construction can bring your dreams to life.

Contact Frei Remodeling & Construction through our contact form to discuss your options and find the right unit for your property.

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Joe Frei

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