8 Secrets to Designing the Perfect ADU, According to People Who Did It

If you’ve ever considered building or buying an ADU, you’re not alone—they’re adorable, practical, and potentially profitable. Accessory dwelling units, or ADUs, are flexible spaces that are perfect for large families, work-from-home hideaways, Airbnb rentals, or a combination of all three. Set apart from a detached single-family home, or tucked into an upper level of a garage, an ADU is the perfect private getaway, just steps away from your front door.

As charming as they are, the prospect of building one might feel daunting. If you’re in the market for an ADU—or simply want some small-space design inspiration—you’re in the right place. We spoke to three ADU owners (and Airbnb hosts!) to get the inside scoop on what goes into designing and building these cute and compact homes.

Why Should You Build an ADU?

Wondering if an ADU is right for you? One reason to make the move is a need for versatile space—an ADU can serve so many different purposes for the same family.

“In the future we might change how we use the space—perhaps it will be a teen hang out spot when our kids are older, or a full-time office space, which is how we used it during the pandemic,” says Diana, who owns a bright and spacious ADU Airbnb in Oakland, California. “It’s great how flexible it is, and, as much as I love my parents, it's so nice when they’re visiting that they can say goodnight and go across the backyard to their own private guest space.”

Aside from providing some much needed space, ADUs can be profitable, too. Kimberly, who owns a small yet dreamy ADU Airbnb in Atlanta, says that it has generated additional income, increased her property’s overall value, and proved to be more cost-effective than a home addition.

“Adding an ADU to your property is like having your own private oasis, complete with a separate entrance and amenities,” says Kimberly. “It’s like having your very own tiny kingdom! And unlike an addition to your home, you can rent out your ADU and become a landlord, so you can finally live out your dream of being a real estate mogul (or at least, pretend to be one).”

What to Know Before You Start

Before you start building, there’s a few things to keep in mind to ensure your ADU is legal, safe, and ready for use. Here’s what ADU Airbnb hosts recommend:

Check Your Area’s Zoning Laws

Before building, make sure you’re allowed to—zoning laws are different from city to city and state to state, and the last thing you want is to find that out when you have a half-built ADU on your property. Some locations have size and rent restrictions that should inform the rest of your design process.

On the other hand, the rules are less restrictive for ADUs in some places, meaning it could be much easier to add one to your property than it would be to build an addition to your home. Learning about your area’s zoning laws might just be the final push you need to decide to go the ADU route.

“While they may not be the most exciting part of building an ADU, think of it as a treasure hunt!” says Kimberly. “You get to go on a wild goose chase to find out what rules and regulations apply to your property, and when you finally succeed, you get the satisfaction of knowing that you've conquered the bureaucracy beast.”

Safety First

Perhaps most importantly, don’t forget to consider safety measures—from the primary design stage all the way to the finishing touches. Simple features like smoke and carbon monoxide detectors, fire extinguishers, and ample emergency exits can make the difference when it matters most, says Kimberly.

Top Design Tips From ADU Owners

There’s a lot that goes into designing an ADU, particularly because they’re smaller than most houses, and are on the same plot as your home. Luckily, these three Airbnb owners are here to share the tips and tricks they’ve learned along the way.

Work With Your Small Space

Because you’re likely working with a smaller area than you’re used to, it’s important to be mindful about optimizing the space you do have. Kimberly says you should follow the classic construction rule of thumb when it comes to ADU floor plans and furniture: Measure twice and buy once.

“Each room and each area has to be both highly defined and uniquely accessible without being overly decorated or filled with furniture,” says Kimberly. “The last thing you want is a sofa that is too big for your living area, or a dining table that is too big for your dining area.”

Storage Is Key

In a small space with shifting uses, clever storage solutions are essential to a comfortable (and uncluttered) stay. Kimberly suggests taking advantage of vertical space by hanging shelves and hooks, incorporating multi-use furniture with storage, building closets and drawers into the ADU’s structure, and avoiding clutter at all cost.

Lean Into Lighting

Lighting is key to creating a comfortable, aesthetically pleasing ADU—and to making a small space feel less claustrophobic.

“Maximize the interior space by adding height and as many windows as you can afford, because sunlight makes a small space feel larger,” says Diana.

Windows, and the natural light they bring, are essential, but there are other creative ways to brighten up an ADU. Kimberly suggests mixing natural light with ambient and task lighting fixtures, and says that installing skylights above the bed and in the bathroom in her ADU really helped open up the space. 

If you don’t have the option to add more lights or windows, consider painting and decorating with light colors—an easy hack to make a space feel lighter and more spacious. Also, in a pinch, mirrors will reflect light around the ADU, giving the illusion of a larger space.

Offer Thoughtful Amenities

Whether you’re building an ADU for your family or for Airbnb guests, you’ll want to make sure to provide everything that your visitors need to feel comfortable, no matter how long their stay. Bathroom and kitchen amenities may seem obvious, but there are some things you won’t want to forget if you want to avoid trips back and forth from the main house—or out to the store.

Stocking the kitchen with pots, pans, utensils, and dishware makes a space feel like home, and adding counter space and modern appliances ensure your guests don’t have to leave the house to find a full meal. 

“Think about the kind of magical experience YOU would like to have, and then begin with the end in mind,” says Kimberly.

Diana also suggests implementing the amenities you might find in a luxury hotel room—a coffee bar, mini fridge, and fresh, white linens—to upgrade your guests’ stay. Plus, making sure your visitors have a comfortable place to work remotely is an added bonus in this work-from-everywhere era, says Isabelle, who owns an Airbnb ADU in Austin.

Take Advantage of Outdoor Space

One of the perks of bringing an ADU into your backyard is the built-in outdoor space that comes with it. A mini patio, balcony, or seating area adds more comfortable living space for guests, and can make a world of difference. Implementing outdoor lighting, too, will help you keep an eye on your space, and will make coming and going much easier for visitors.

Also, keep the garden in mind! Kimberly says that an outdoor plant display can quickly become an ADU’s best friend.

“Because the outdoor space is probably going to be small, don’t be afraid to go wild or experiment with your foliage options,” she says. “We use copious amounts of ferns, wild ivy, flowers, plants, and other things to give the small outdoor space a forest/tropical vibe.”

Don’t Forget About Privacy

Something ADU hopefuls often forget about is privacy—for guests and homeowners alike. Whether you install partition walls, small fences, gates, or doorways, creating a barrier between the ADU and your home will ensure that nobody intrudes upon anyone else’s space. 

“Think about how the ADU can fit into your backyard and how you will enter and exit—we really value having a separate private entrance to our backyard so that guests can come and go as they need,” says Diana.

Diana also says that her family takes advantage of a “strategically located maple tree,” and communicates with guests about when they need to use their shared backyard space. She says that she reserves her own Airbnb for a few weekends over the summer so that her family can take advantage of the space themselves—you should get the chance to enjoy your brand-new ADU, too.