The Best ADU Interior Design Ideas for Your Backyard Builds

If you want to add a guest house, a detached home office, or an in-law suite for extended family, an accessory dwelling unit (ADU) can expand the utility of your home without tying you up in renovations for too long. But how can you make these small spaces feel comfortable and welcoming? We’ve rounded up the best ADU interior design ideas to make your granny flat a grand success. 

ADU interior design: The Outpost bedroom

What Is an Accessory Dwelling Unit?

An accessory dwelling unit, or ADU, is a structure on your property that can either be separate from or attached to your main house. An ADU can serve many purposes, from a home office to a guest house, and can even act as a long-term living space.

ADUs aren’t a modern invention. They're sometimes known as carriage houses, in-law units, garden suites, or granny flats. Before retirement communities became the norm, granny flats offered dignity and independence to older adults while keeping them close enough to get any needed care and stay connected to family members.

Nowadays, an ADU can be much more than a place for Grandma. If you want to add a rental property, a creative studio space, or a home gym, a detached ADU can do it all. With enough space, you can even set up a cluster of tiny houses for a communal living space or a group of renters.

In addition to rental income and having space for guests, homeowners can also enjoy how adding an ADU benefits their property values — homes with ADUs are priced 35% higher on average.

In most cases, the desired function of your ADU will dictate your design choices. But there are some guiding principles for ADU interior design that will help you make the most of these small spaces.

ADU Interior Design 101

Tiny homes and small cabin plans lend themselves to a variety of decor styles. Your ADU interior design can be inspired by the modern farmhouse, rustic cottage, or even upscale art deco style. However you plan to decorate your ADU, here are some basic home design features that will help open up any dwelling with a small floor plan


ADU interior design: A-Frame Bunk Cabin

There's nothing like natural light to make a room feel spacious and airy. When you're dealing with limited square footage, windows add openness and style without requiring more space — perfect for an ADU design with a small footprint.

A picture window enhances the roominess by brightening the inside of your small space, while floor-to-ceiling windows can give your backyard cottage a high-end feel. If you have an impressive view or a garden, these large windows serve to integrate your ADU into your property. And they work for designs of all sizes, even our 196-square-foot A-Frame Bunk Cabin, which boasts a 14-foot-high wall of glass to ensure you never feel closed in.

If you want natural light and more privacy from the main house, try moving the windows to the top of your ADU design. Skylights and clerestory windows suffuse your interiors with natural light without putting your windows on display. 

Multipurpose Rooms and Furniture

ADU interior design: woman fixing a bed

Creating a functional dwelling without sacrificing too much of your living area space can be a challenge. One way to maintain a balance is by including multipurpose furniture and spaces in your ADU. Fortunately, the tiny house community is packed with ingenious space-saving ideas like convertible furniture and creative storage. For example, a sofa bed — or a Murphy bed, like you'll find included in a DEN Outdoors Shed Tiny House — can allow a one-room dwelling to meet many of your needs. Once the bed is stowed, the sleeping area becomes an office, dining room, or workout area. 

Outdoor Spaces

With tiny houses and small modern homes, your outdoor spaces are nearly as important as the interiors. A deck, patio, or outdoor living room can help a small ADU feel bigger and more connected to your property. You can extend your indoor features with outdoor furniture, an awning, and heaters to create comfortable exteriors even in cold weather. Or you can step up your gardening game and create a beautiful natural setting for your tiny home. 

ADU Designs to Fit Your Home

The size and style of your ADU depends on your main house, how much space you have on your property, and how you want to use this additional dwelling. Some homeowners opt for a compact tiny home, while others may choose to build multi-story units that will seem like a home away from home.

Small ADU Designs for Guest Houses

If you want to have a detached space for your guests to stay in, or for short-term renters, these DEN tiny house and small ADU plans are perfect — especially if you only have a little room to work with on your property. Each one comes in at 200 sq. ft. or less, and they include features that make those compact floor plans feel spacious. 

Tiny House 2.0 

ADU interior design: Tiny House 2.0 bedroom

This 144-square-foot ADU makes a cozy addition to your property, but the wall of windows and stowable Murphy bed make the Tiny House 2.0 feel open and flexible. You or your guests will have all the essentials with a kitchenette and full bathroom, and our over-the-top storage loft keeps the clutter at bay.

ADU interior design: living room with frames hanging on the wall

You can go for modern and minimalist decor to complement the floor-to-ceiling windows. Soft colors will amplify the size of your space, and you can add variety and texture with patterned rugs and houseplants. 

Cottage Tiny House

ADU interior design: Cottage Tiny House

The classic Cottage Tiny House will add storybook charm to any property while offering accessibility and functionality. The full kitchen and bathroom, dedicated living room, and cozy alcove bed make for comfortable quarters where you can curl up by the wood stove or take in the views through the four picture windows.

Wooden-themed kitchen

Emphasize the classic cottage vibes with a rustic ADU interior design. Wooden decor, white furniture, and the contrast of black metal hardware will transport you to a country cottage when you walk in the door. For a more modern variation, go for muted pastel instead of white for walls and cabinets. 

Medium ADUs for Long-Term Living

The granny flat gets an upgrade with these larger ADU plans, making them ideal additions for family members or long-term renters. These designs include the comforts of home in a smaller package, so your guests can stay as long as they want. 

Modern Alpine Cabin

Modern Alpine Cabin

An elevated version of our tiny house designs, the 448-square-foot Modern Alpine Cabin takes your ADU to the next level with 19-foot ceilings, striking skylights, and a lofted bedroom. The option of a full glass wall and the wraparound decking add plenty of light and outdoor space to your stylish ADU

Green couch, a plant, and a round rug

Lean into the cottage style with modern farmhouse decor, or go for something more glamorous with neutral walls, jewel-toned furniture, and gold accents. The clean lines and bold style of this cabin offers a flexible canvas for your ADU interior design choices. 

Essential Retreat

Essential Retreat

The Essential Retreat offers 550 sq. ft. of space with floor-to-ceiling windows and a front deck that's perfect for lounging in the open air. Add an awning and heaters for a year-round outdoor living room, or further integrate the design with your surroundings with a patio garden.

With the simple lines of the Essential Retreat, the ADU interior design for this build can go toward classic decor or more adventurous styles.

Backyard Office ADU Designs

Whether you're working from home, creating your next big project, or just looking for a place to be at peace, these versatile detached office designs will give you space for whatever you need to do. Each has been thoughtfully designed to make your ADU office a productive and comfortable place to get to work. 

The Office

The Office

Working from home doesn't have to mean hunkering down in the hall closet or battling for the spare bedroom. Instead, take a stroll through your backyard to this petite, 130-square-foot ADU that's sure to perk up your productivity. The Office is ideal for storing your library, creating content, or giving you a space to create and be inspired by the natural world through the huge windows. With room for a sitting area, you can even meet with clients or creative partners.

Emphasize the nature-friendly design of this build with earth-toned decor and natural wood furniture. Your interior design choices should help create a productive workspace for you.  

The Pod Plus

The Pod Plus

The 140-square-foot Pod Plus brings the added convenience of a bathroom to your backyard office, so it's perfect for longer workdays. You can even add a pull-out sofa bed and an outdoor kitchen setup for a local retreat. This cozy space would look great with a country cottage interior that accents its natural charm. 

Find the Right ADU Design at DEN

ADU interior design can take a classic route with modern farmhouse or rustic cottage styles, but you can also incorporate upscale elements in these small spaces. Remember to include features like large windows, multipurpose rooms, and thoughtful outdoor spaces to make the most of your square footage.

Whether you want a rental property, a detached workspace, or living quarters for family members, you can find the best house plans for your ADU at DEN Outdoors. Our library of plans includes designs for tiny houses, small cabins, and even full-size barndos, so you can find exactly the kind of ADU you're looking for.

We stand behind our expertly designed plans, but we want your ADU to fit your specific needs and style. We're happy to work with you to customize your ADU plans. With a Complete package, you can build the perfect DEN for you. 




  • Study: ADUs can add 35% to Home’s Value. (2021b, November 4).
  • Allen, E. (2017, January 16). See how clerestory windows can transform a room. Architectural Digest.
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  • Rabideau, C. (2019, January 30). 10 tiny houses where the yard steals the show. Food52.
  • What is an ADU (Accessory Dwelling Unit) | Building an ADU — Building an ADU. (n.d.-b). Building an ADU.