What is an ADU?
An ADU, or Accessory Dwelling Unit, is a self-contained living space on the property of a primary residence. In addition to bedrooms, they also have their own bath and kitchen. Before they were called ADUs, though, they were also known as Granny Flats, In-Law Units, and Backyard Cottages.
As of 2021, ADUs made up roughly 2% of all homes in the country. Of those properties, 30% of them are in California, which eased restrictions in 2016. So, if it feels like ADUs are brand new, that may be due to how many have popped up since that ruling.
ADUs are a great way to add more space to an existing property. ADUs can accommodate guests, give you extra living space, and increase your home value. But, they’re not to be confused with Tiny Houses or other types of minimalist living. Let’s look at a few of the key differences.
ADU vs. Tiny Houses
Tiny houses are all about making the most out of tight quarters. Image courtesy of mydomaine.com
One crucial difference between tiny houses and ADUs is the square footage. A tiny house is typically only 100-400 square feet, whereas an ADU can be up to 1200 square feet! Additionally, tiny homes are often built on a trailer foundation, which allows them to be relocated easily. ADUs, on the other hand, are permanent structures. One other key difference between their sizes is building height. Tiny houses can only be one story, whereas ADUs can often be up to two stories.
Tiny houses also differ because they’re characterized by a simplified, minimalist lifestyle. While they do have amenities like a shower and a bathroom, they place a greater emphasis on space saving. Because of their limited square footage, you’re likely to find functional design aspects such as modular furniture in tiny houses. While ADUs may feature some of those design aspects, it’s not usually as big of a focus as it is for tiny houses.
The two main types of tiny houses are permanent or mobile. In states like California, you can only legally have a permanent tiny home if you obtain a special use permit. If it’s mobile, though, you can get a tiny house without a special permit. You can connect your tiny home trailer to an RV park, and all you have to do is drive in!
When it comes to ADUs, though, there a few different types to choose from.
What Are the Different Kinds of ADUs?
Two types of ADUs are attached and detached, illustrated here. Image courtesy of danville.ca.gov
First, there’s the detached ADU, which stands away from a primary residence. They’re commonly found in backyards, but they can be placed anywhere on the property as long as you meet your area’s setback requirements. In California, detached ADUs can range in size from as small as 150 square feet to as large as 1200 square feet. However, size restrictions do vary due to different cities’ zoning regulations.
The second type of ADU available is the attached ADU. This is an ADU that’s built onto the primary residence. Despite being attached, they can still be a similar size to a detached ADU. For areas without an ADU ordinance in California, attached ADUs can range in size from 800 square feet to as big as 50% of the floor area of the existing house.
However, it’s important to note that regardless of whether the ADUs attached or detached, it must have a full kitchen, bathroom, and living and sleeping spaces. Because of these requirements, some homeowners prefer to build a Junior ADU instead.
A Junior ADU is like an ADU, but it’s allowed to share features with the primary residence. Junior ADUs are also smaller, with a maximum size of 500 square feet. They have to be contained entirely within a single-family residence, and they need to have a separate entrance from the main house. While they can share a bathroom with the main house, Junior ADUs are still required to have their own efficiency kitchen. But, unlike a full-size ADU, JR ADUs also come with an owner occupancy requirement. So, if you’re planning on traveling or living away from the main residence, the JR ADU may not be right for you.
ADUs can be designed new or built from pre-made frames like this one. Image courtesy of homedepot.com
However, ADUs don’t have to be newly constructed! You can always convert an existing structure into an ADU, such as a garage, to save some space and cut costs. As long as it has a full kitchen, bathroom, and living and sleeping spaces, converting an existing structure is a great way to add more guest space to your home.
The other benefit of converting an existing structure is the special setback requirements. If you expand your existing structure 150 feet or less beyond its original dimensions, your ADU doesn’t have to be as far from the edge of the property as one that’s newly constructed.
But regardless of what type of ADU you’re interested in, be sure to take a look at your county’s ADU guidelines before you get started. In Santa Clara County, for example, homeowners can build up to one ADU and one junior ADU provided that you meet county standards regarding water and sewage, setback requirements, and fire safety. However, ADU allowances and size restrictions can vary between counties, and even between cities within a single county.
Which Type is Right for You?
ADUs may be a good fit if you have a large yard, such as this one. Image courtesy of Milpitas.gov
So, which choice is right for you? ADUs may be a good fit if you’re looking to build a separate living space for family, or create a new space for an additional living area, home office, or studio. They have the benefit of spaciousness, which can be good for extended stays. However, that spaciousness means that you need enough of space on your existing property to build or convert one. A tiny house may be a better fit for you if you don’t have a large property or are looking for a more mobile option. Whichever you choose, though, space planning is essential. If you need any help with designing your space, reach out to us at HArts Design+Build and we’d be happy to help. Plus, check back here for more tips on modern living spaces in the future!
