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What States Allow Accessory Dwelling Units: Everything You Should Know

There are many ADU-friendly states, some of them being:

  • Idaho
  • California
  • Oregon
  • Maine
  • Connecticut
  • Washington
  • New York

Most of these states have introduced recent ADU bills. These bills facilitate the development of accessory dwelling units (ADUs). Some of them have also updated zoning laws to permit accessory dwelling units. These secondary homes on residential properties provide extra living space. They also help cities address housing shortages. However, each state has distinct regulations to address their unique needs. These concern ADU size, who can live in them, and more.

This article will cover some of the ADU regulations in states that allow them, as well as the benefits and other practical details. Keep reading to learn more!

What Are ADUs?

ADUs, short for Accessory Dwelling Units, are small secondary homes. These homes must be situated on the same property as a primary residence. They provide additional living space separate from the main house.

ADUs allow homeowners to accommodate family members, take on renters, or use them as home offices. They also help increase housing options for people that don’t have as much of a budget to work with.

The Perks of Accessory Dwelling Units

ADUs are becoming more common because of the benefits they offer families, renters, and would-be homeowners. Here are just a few of the benefits that come with secondary units:

  • Allows Building More Homes without New Land: ADUs can be constructed on existing properties without extensive new land development, which can be time-consuming and costly. These smaller units help increase housing stock efficiently, whether building a standalone or detached ADU, an attached ADU, or an interior ADU (like a converted garage or basement apartment). ADUs enhance the existing housing stock by utilizing unused spaces like garages and basements, maximizing the functionality of properties.
  • Supports Multigenerational Living: ADUs provide a great setup that allows families to stay close while maintaining privacy. This arrangement improves family connections and can also help with aging in place with the support of loved ones.
  • Increases Density in the Right Way: ADUs allow cities to increase urban density without the downsides of overcrowding. By adding ADUs to existing homes, neighborhoods can have more housing without changing their appearance.
  • Offers Diverse Housing for Everyone: ADUs contribute to various housing needs. They provide housing solutions for all, including young professionals seeking affordable urban spaces and seniors looking for downsized homes.
  • Provides Economic Advantages for Homeowners: ADUs offer an economic advantage by providing affordable housing options in urban areas where the cost of living is typically high. Homeowners can generate rental income by renting out the extra space, which can help cover mortgages.

Federal Regulations on ADUs

While no specific federal regulations govern ADUs, federal laws and policies can still significantly influence state laws surrounding ADU development and construction. For instance, the Fair Housing Act ensures that ADUs are accessible and do not discriminate against certain groups, promoting inclusivity in housing. Similarly, the Americans with Disabilities Act (ADA) may apply to ADUs, ensuring they are accessible to individuals with disabilities.

Additionally, federal funding programs can provide financial assistance for ADU construction and rehabilitation. The Community Development Block Grant (CDBG) program, for example, offers funding to support the development of ADUs. These grants can help homeowners and local governments finance the construction of ADUs, thereby increasing the availability of affordable housing options.

By understanding how federal laws and funding programs can impact ADU development, homeowners and developers can better navigate the process of building these valuable secondary housing units.

States that Allow ADUs

Several states have enacted laws and regulations that permit the construction of ADUs. These states recognize the potential of ADUs to address housing shortages, increase affordable housing options, and provide additional income for homeowners.

Idaho

In 2023, Idaho passed legislation that prevents local governments and HOAs from banning ADUs. The legislation also allows for “reasonable” regulations, such as parking requirements and size limits.

Idaho cities, including Boise, have updated their zoning codes in line with state law to make it easier to build ADUs. In 2019, Boise eased restrictions on ADUs, increasing the maximum size from 600 to 700 square feet and allowing up to two bedrooms.

In 2023, Boise’s new zoning code increased the maximum size to 900 square feet and eliminated the requirement for dedicated parking for single-bedroom units.

During the pandemic, families used ADUs to increase their living space. Since then, the rising cost of living and interest rates have contributed to the continued popularity of ADUs.

ADU ordinances are becoming more and more favorable in the Treasure Valley area.

California

California is a leader in ADU-friendly legislation. In 2020, the state passed Assembly Bill 68 (AB 68), which allows ADUs to be built on lots as small as 1,200 square feet. The bill also streamlines the permitting process and reduces restrictions on ADU construction. California’s laws aim to increase the supply of affordable housing and provide more options for homeowners and renters.

You might also like: Lessons from Spacial Homes: Pioneering ADUs in the Bay Area or United Dwelling: The Rise and Fall of an Innovative ADU Solution in Los Angeles

Oregon

Oregon has also taken significant steps to encourage ADU development. In 2019, the state passed House Bill 2001 (HB 2001), which allows cities to adopt ADU-friendly zoning codes and requires them to allow both attached and detached ADUs. Oregon’s ADU laws and local ordinances are designed to increase the supply of affordable housing and provide more options for homeowners and renters.

Maine

Maine’s ADU laws are designed to increase the supply of affordable housing and provide more options for homeowners and renters. In 2022, the state passed LD 2003, which allows homeowners to add an attached or detached ADU to plots zoned for single-family use. The law requires ADUs to be at least 190 square feet and bans cities from setting parking requirements beyond those existing for single-family homes.

These states and others are working to address the housing shortage and provide more affordable housing options through ADU legislation. By understanding the laws and regulations governing ADUs, homeowners, and developers can take advantage of these opportunities and contribute to the growth of affordable housing.

Connecticut

Connecticut has created regulations that encourage existing homeowners to build ADUs on their property. Their ADU law and regulations include:

  • Single-family homes across the state are permitted to have ADUs, with certain exceptions related to environmental factors.
  • ADUs are permitted by right, so city officials don’t need to give any special approval.

Washington

Washington State actively supports ADUs and has recently passed legislation, particularly House Bill 1337, which significantly eased restrictions on building ADUs across the state, taking effect in July 2023; this is considered a major step towards promoting more affordable housing options within the state. Some of the key ADU regulations include:

  • Each lot can have up to two ADUs.
  • The state has removed the rule requiring ADUs to have a specified number of parking spaces.
  • Washington has removed the requirement that property owners live on the premises to build an ADU.

New York

New York is encouraging homeowners to build ADUs to address housing shortages. Specifically, the Plus One ADU program is supporting these efforts. It offers low or no-interest loans and construction grants to help homeowners increase the capacity of their livable space.

They have also proposed legislation to support the development of ADUs. These regulations intend to increase housing options and decrease housing costs. The state does set general guidelines, however, local governments have significant control over ADU regulations.

Arizona

In Arizona, the cities make their own regulations, even though the state allows ADUs. The larger cities must allow at least one ADU per single-family home (with size limits). However, some cities like Phoenix and Tucson have their own ADU policies.

Texas

Texas is worth mentioning even though it doesn’t have any statewide ADU laws. Certain areas, like Austin are very open to ADUs, while others are strict about them.

If you are interested in adding an ADU in Texas, it’s worth looking up the city you want to build in.

North Carolina

North Carolina allows ADUs, but cities and counties determine the specific rules locally. If you aren’t sure what the local laws are, you can check your local zoning codes to understand the ADU guidelines in that area or reach out to ADU advocates.

Florida

Florida allows ADUs, but the regulations can vary significantly by locality. The state allows local leaders to set ADU rules but requirements may be different across cities and counties.

Massachusetts

Massachusetts permits ADUs, but the regulations can vary greatly between different cities and towns. No statewide standards exist, so local jurisdictions can decide size limits, occupancy rules, and other ADU requirements. Some areas have more strict regulations and require ADU permits for homeowners to build.

How to Add an Accessory Dwelling Unit to Your Property

Now that we’ve covered some of the states that allow an ADU, here is how you can go about adding these secondary units, assuming you live in an ADU-friendly place:

  1. Decide on an ADU Type. First, determine what you want to use the ADU for: do you want to rent it out, house family or guests, or have a home office? This will help you decide the type and size of ADU that best suits your needs.
  2. Come Up with a Budget. Get estimates from a few different local contractors, like True-Blue Construction, with experience in ADU construction. This will help you determine how much you’ll need for the project.
  3. Finance Your ADU. Like many homeowners, you’ll probably need financing to complete your ADU project. Fortunately, you can explore several financing options, including refinancing your mortgage or doing a cash-out refinance. However, if you prefer more borrowing power, even if you don’t have substantial equity in your home, consider taking out a home renovation loan. This option lets you access a significantly higher percentage of the after-renovation value of your home. Plus, you get to pay less in interest and lower fees.
  4. Get Permits and Approval. Although you may live in a state that allows ADUs, you still need to get all the necessary permits before you start construction. It’s also important to make sure you build your ADU to comply with your area’s zoning code and regulations.
  5. Work with a Professional. Consider hiring a design-build ADU company like us. This way, just one team will handle everything, including designing, permitting, and the physical construction. Besides, working with an expert ADU builder ensures your project meets local codes and regulations.
  6. Begin the Construction. With all the permits in hand, you can start construction. After the construction phase, the unit must pass final inspections before you can use it for your desired purpose.

What to Consider When Planning Your ADU and ADU Laws

As we have covered, specific ADU regulations vary between state and local governments. As such, here are some things you’ll want to consider when designing your accessory dwelling unit:

  • Density and Size Constraints: The first step is understanding the density and size limitations of ADUs in your area. Local jurisdictions often set rules around the maximum square footage or how much of the lot can be occupied by the ADU in relation to the primary dwelling. Be sure your design plans fall within these constraints to avoid issues down the line. Understanding local regulations related to different types of ADU units is crucial to ensure compliance.
  • Structural Design: When deciding the height of the physical structure, pay close attention to height restrictions. ADUs may have lower maximum heights than the main house, so work closely with your contractor to ensure your design meets local building codes.
  • Site Conditions: Look closely at the specific site conditions where you plan to build the ADU. Factors like the slope of the land, drainage patterns, and soil quality can all impact the feasibility and cost of construction. Addressing these early on during the planning phase can save you headaches later.
  • Parking Requirements: Many areas have relaxed parking rules for ADUs, especially if the unit is located near public transit. However, it’s still important to confirm if any off-street parking is required and incorporate that into your site plan.
  • Access and Entry: It’s important to ensure safe, accessible entry to the ADU. This may involve adding a walkway from the street or strategically positioning the entrance for privacy. Basically, you should factor in how tenants and visitors will access the unit.
  • Interior Design: When designing the unit’s interior, maximize the limited square footage. Built-in storage, space-saving furniture, and efficient appliances can help create a comfortable living space.
  • Utilities: Running utilities such as water, sewer, electricity, and gas to the ADU takes some planning. You’ll need to consider where the main utility hookups are and the best way to connect the ADU. The location of the ADU on your property will depend on where it’s easiest and cheapest to bring in the utilities.

Let True-Blue Construction Help You Bring Your ADU Construction Vision to Reality

These accessory units provide affordable places to live. They also provide new housing and help with familial problems. Because of this, many states have modified their zoning codes and regulations, legalizing ADUs, to encourage homeowners to construct these smaller living spaces.

If you’re a homeowner in one of the states that allow ADUs and are ready to get started, give True-Blue Construction a call!

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