Seattle Backyard ADU: Metal Exterior, Warm Wood Interior

A compact backyard house that functions as a self-contained dwelling brings real flexibility to urban living. For some owners it serves as a second home while they travel or rent out the primary residence; for others it becomes a welcoming guest space for family and friends. It can also be a private retreat for a couple seeking a simple, peaceful escape. The Alley Cat Backyard Home in Seattle was created by SHED Architecture & Design to meet exactly this kind of lifestyle: a modest Detached Auxiliary Dwelling Unit for a couple who split their time between the city and the Southwest while renting their main house.

Alley Cat Backyard Home exterior — Space-savvy and open design of the Alley Cat Backyard Home in Seattle with ample natural light

The house takes its playful name from a roofline that, with its angular profile, seems poised and ready to move through the streetscape. The exterior is clad in standing-seam metal plates, giving the façade a durable, low-maintenance finish that resists weathering and reads as contemporary against the neighborhood context. Inside, the metal exterior gives way to a warm interior palette of white and wood. Wood-paneled walls throughout the home establish a midcentury-modern warmth that feels both familiar and modern—an aesthetic common in Seattle homes but executed here with careful restraint.

Sliding glass doors connect the interior with the garden — Creating smart connectivity between the living area and the garden using sliding glass doors

Large sliding glass doors open the principal living space directly to the garden, blurring the boundary between inside and outside and extending the sense of space on warm days. Expansive windows and well-placed skylights introduce abundant daylight into both the main floor and the loft, while thoughtful sightlines make the compact plan feel generous and airy. The interior balance of natural wood and crisp white finishes keeps the rooms feeling calm and bright, providing a neutral backdrop for varied furnishings and seasonal accents.

Interior connecting to garden through sliding doors — Large sliding glass doors easily connect the spacious interior with the garden

Small living room with minimal decor — Minimal decor and a space-conscious design give the small living room a larger visual appeal

Every design decision emphasizes efficient use of space and year-round comfort. Heated concrete floors provide comfortable warmth through colder months, while a loft level creates additional sleeping or storage space without increasing the building footprint. The loft overlooks the living area and benefits from the same daylighting strategy, making it feel connected rather than cramped. Minimal, modern décor keeps sightlines clear and reinforces a feeling of openness.

Overall design gives a modern mid-century vibe — Overall design of the backyard house gives it a modern mid-century vibe

View from the loft into the living area — View of the small living area with wooden panel-covered walls from the loft level of the backyard house

Interior palette of white and wood — White and wood palette on the inside is combined with standing seam metal plates on the outside

Small details elevate the interior: a chevron-tiled bathroom floor adds pattern and texture; a tropical-style ceiling fan introduces a relaxed, airy mood to the bedroom; and skylights intensify natural illumination in both the bathroom and loft. Together, these elements create a compact but polished home that feels comfortable in all seasons. The combination of low-maintenance exterior materials and thoughtful interior systems—daylighting, radiant heat, and efficient spatial planning—makes the Alley Cat Backyard Home a practical and inviting addition to an urban lot.

Interior showing wood, white and heated concrete floors — Wood and white along with heated concrete floors shape the interior of the house

Wood panels, white surfaces and large glass windows — Wooden panels combined with white and large glass windows to create a beautiful Seattle second home

Bedroom with a tropical fan — Beat the heat in the bedroom with a tropical fan

Chevron tile bathroom floor — Interesting use of chevron pattern tile for the bathroom floor

Skylight illuminating the bathroom and loft — Skylight brings ample natural light into the white bathroom and in the loft level as well

Photographs: Mark Woods. The Alley Cat Backyard Home is a clear example of how thoughtful design can make a small footprint feel much larger and more capable than its size suggests—an excellent model for homeowners looking to add flexible living space to an urban property without sacrificing style, durability, or comfort.