1BR/1BA 31×13 Long

Smart Design for Small Spaces: 400 Sq Ft ADU Plans

Our ADU floor plans are designed to maximize space without compromising on comfort. As one of the most popular sizes for small accessory dwelling units (ADUs), these ADU floor plans at 400 sq ft are perfect for homeowners looking to add a functional living space to a smaller backyard. With a narrow 13.5 ft width, this one-bedroom, one-bathroom design is ideal for urban lots or properties where space is at a premium.

Ideal for Narrow Backyards: 14 Ft Wide Design

One of the standout features of this just under 450 sq ft ADU floor plan is its narrow design, stretching just under 14 feet wide. This compact dimension makes it a great fit for properties with tight space constraints. Whether you want to transform an underutilized section of your backyard into a functional living space or provide independent accommodation for a family member, this ADU can fit seamlessly into your property’s layout.

The design is thoughtfully crafted to make the most of every inch. Upon entering through the front door, you’re greeted by an open-concept living room and kitchen area, creating an inviting atmosphere that feels spacious despite its small footprint. This efficient layout ensures the main living areas flow seamlessly together, perfect for someone looking to simplify their lifestyle by downsizing or create a cozy guest rental. Walking down the hall, you’ll find a full bathroom and a bedroom large enough to fit a queen-size bed. While this ADU omits a laundry area to save space, it offers all the essentials for modern living, making it a practical option for backyards with limited room to expand. If you have want a little bit more square footage and laundry, you might like our 1BR/1BA 37X13 Narrow Floor Plan.

A Versatile Space: Ideal for Rental Income or Family Living

This 400 sq ft ADU floor plan offers exceptional flexibility, making it a perfect choice whether you’re planning to generate rental income or create a comfortable space for a family member. As a rental unit, its compact yet efficient layout is appealing to tenants looking for a cozy, self-contained living space. The bedroom is spacious enough to accommodate a queen-size bed, making it a desirable option for singles or couples.

For those considering the ADU as a home for a family member, the design ensures a comfortable and independent living experience. Whether it’s for aging parents or adult children, the floor plan offers everything needed to support a modern lifestyle. The open-concept design encourages easy movement, while the separate bedroom and full bathroom ensure privacy and comfort.

Its compact size also allows for easier maintenance, keeping upkeep simple and stress-free for both tenants and family members.

Despite it’s small size, this floor plan is still considered an ADU instead of a tiny home. Read more about ADUs vs. Tiny Homes.