Best ADU Designs

Key Takeaways

The best design for your accessory dwelling unit often comes down to factors like budget, lot size and shape, and intended use. Homeowners looking to use their ADU as a home office or occasional guest house may want a studio apartment layout, while those looking to use their ADU as a granny flat or source of rental income may get the most out of a 1-bedroom or 2-bedroom layout.

No matter your floor plan, there are certain design practices to keep in mind when it comes to your ADU’s interior. These design practices, like increasing natural light, opting for open-concept living areas, and utilizing vertical spaces, may sound small on their own – but add them all together, and you can seriously increase your ADU project’s functionality and sustainability, as well as its overall return on investment.

Keep your end goal in mind. Your ADU’s layout should reflect how you plan to use it—guest suite, rental, or office—to get the best return on space and investment.

The Most Popular ADU Designs

While pre-designed ADU plans are less expensive than custom plans, it’s the customization that will ultimately help you get the most out of your investment when it comes to livability, durability, and (for those looking to rent) additional income.

While we hope these popular floor plan designs show you what’s possible when it comes to your additional living space, also think about what design changes would create a more functional space for your property and your family.

Best Studio & 1 Bedroom Designs

Homeowners with limited lot space or budget or who intend on using their ADU as an office, hobby space, or guest space may find they get all they need with a studio layout like this one. You can see the living room is open to the u-shaped kitchen and has room for a pull-out couch, a table, and built-in storage. Though only 360 square feet, a backyard cottage with this design makes a comfortable workspace or weekend getaway spot.

Though studios can be used to house adult children or aging parents, if you intend on using your ADU for full-time living, a 1-bedroom design will be more comfortable. And as you can see here, adding a primary bedroom to your layout doesn’t necessarily mean a much larger footprint. This popular house plan is only 400 square feet and offers an open-concept living room and kitchen, a private bedroom, and a full bathroom with a tub and dedicated laundry space. All of these additions (the private bedroom, tub, and in-unit laundry) can give even a small in-law suite all the functionality of a single-family home. Of course, 1-bedroom ADUs don’t have to be small. See 1-bedroom ADU plans of all sizes here.

Smaller spaces thrive on function. Prioritize open-concept layouts, built-ins, and light-enhancing elements to make every square foot count in a studio or 1-bedroom ADU.

Best 2-3 Bedroom Designs

If you’re hoping to provide a space where multiple aging parents or adult children can live, or you’re looking to maximize your rental income, an ADU with at least 2 bedrooms is ideal.

2-bedroom ADUs are among our most popular designs, and the possibilities are endless. This layout epitomizes space optimization, comfortably fitting 2 bedrooms with closets, a full bathroom, and a dedicated laundry space into only 500 square feet, while this one provides dedicated outdoor living space (much desired in the San Diego area!). This layout helps homeowners make the most of narrow single-family lots or even side yards.

Adding an additional bedroom and building a 3-bedroom ADU helps families achieve true, long term multi-generational living. Typically, 3-bedroom units are at least 1000 square feet and contain 2 bathrooms, one of which can be an en-suite, creating a master oasis.

For more inspiration, check out our 2-bedroom and 3-bedroom ADU plans pages.

More bedrooms, more potential. Two- and three-bedroom ADUs can support multigenerational living or boost rental income—without compromising comfort or style.

Modern Minimalism

When it comes to secondary living spaces, choosing the floor plan is just the first step. The overall design style you choose not only increases the comfort and appeal of the space but also makes it more attractive to renters – resulting in extra income.

Minimalist, modern designs are not only popular, but they are also a natural fit when it comes to compact spaces, helping them to feel as large as possible. These kinds of interiors are defined by clean lines, limited or neutral color palettes, and purposefully chosen furniture.

Design with intention. Modern minimalist interiors keep your ADU feeling spacious and serene, especially in smaller layouts where every element has a purpose.

Coastal Living

Of course, in California, the coastal design style is incredibly popular, especially in ADUs. This kind of design incorporates lots of blues and greens (naturally) but also plays up other natural elements and textures, too, such as wicker or wood. It’s ideal for creating a calm, relaxing backyard retreat.

Bring the outdoors in. Coastal ADU design uses natural materials and light colors to evoke calm and make the most of San Diego’s sun-filled lifestyle.

Rustic, Farmhouse Charm

For homeowners with a more traditional design aesthetic or who want to provide a homey space for aging parents, an ADU with a more rustic or farmhouse aesthetic may be the right choice. Farmhouse design typically features natural elements like exposed beams or shiplap walls, as well as stone countertops and vintage furniture, all of which give the space a cozy, lived-in feel.

Key Design Elements to Consider

Whatever design style you choose for your ADU—modern, coastal, farmhouse, or something else—it’s important to remember that designing an ADU is different from designing a single-family home, and there are key design elements that transcend style and make smaller spaces feel as large and comfortable as possible. These include layout optimizations, maximizing light and vertical space, and creating energy efficiency.

Function begins with planning. Smart ADU design starts on paper—prioritize natural light, optimized layouts, and vertical space from the earliest drafts.

Optimize Layout for Functionality

Whether your ADU is 400 square feet or 1000, there are small adjustments you can make to your layout that can make the space more functional and increase flow. For example, in many of our own ADUs, you’ll notice that we like creating kitchens that utilize c-shaped or u-shaped kitchens. This increases the cabinet space and functionality of the kitchen without adding more square footage.

Open-concept design is also key in these spaces. By extending the sightlines in the main living space, you make the ADU feel larger and more spacious (especially when you employ the design elements we get into next).

Maximizing Light and Space

The more natural light a space has, the brighter it will feel. We give the ADUs we design more natural light by utilizing vaulted ceilings and light wall colors. We will also often draw the eye up with built-ins or open shelving. This not only makes the room feel larger but also adds additional storage space, which is especially important in small living spaces.

For more design tips for ADUs, check out our separate post here, which is filled with all our best ideas.

Light transforms small spaces. Use windows, reflective surfaces, and ceiling height to make your ADU feel open, airy, and inviting—even in compact layouts.

Energy Efficiency and Sustainability

Certain energy efficiencies and sustainability measures, like solar panels, are often required in California as part of Title 24. However, they can also be a smart choice in helping offset ADU costs like electricity in the long run, making the home more sustainable and affordable.

Elevate Your Space with Better Place Design & Build

Whatever the perfect ADU means to you, we want to bring your vision to life. Our #1 goal is to ensure a stress-free construction process from start to finish so you can enjoy this exciting next step for your home and your family. From custom designs to construction details to the permit process, we handle it all. And it all starts with a free consultation.

Your dream space, made simple. Our turnkey process takes your ADU from concept to completion with expert guidance and a stress-free experience every step of the way.