One-bedroom detached ADU

A compact, well-designed 1-bedroom detached ADU that’s easy to place on a wide range of lots—without feeling cramped inside. The layout is efficient and livable, with an open living/kitchen area, a true bedroom, and smart storage built in throughout.

With a clean, timeless exterior and a straightforward footprint, this design is a strong fit for homeowners who want a backyard home for rental income, multigenerational living, or a dedicated guest space—while keeping the build practical and predictable.

Pricing

Backyard homes are priced as five packages, from $297,049. See the packages and prices →

2026 proposal prices. Each package price includes construction, the builder’s fee and design & engineering; permits, utility and connection fees, and sales tax are extra. A fixed price for this plan on your lot comes after a site visit and design. Seven to fourteen months from design to move-in.

Key seattle DADU features

• 550 SF / 1 Bed / 1 Bath compact layout designed for comfortable everyday living
• Open living + kitchen concept that feels bright and spacious
• Walk-in closet (WIC) for real storage (not just a reach-in)
• Dedicated pantry + stacked laundry integrated into the plan for convenience
• Simple gable roof form and clean exterior lines that work across many home styles
• Flexible finish options for siding, trim, and color to match the main house or create contrast

What’s Included in the Seattle DADU plan set?

This plan set gives you a solid, buildable foundation to move forward with a detached ADU—including the key drawings needed to define the design, layout, and exterior appearance.

Typically included:

• Floor plan layout and dimensions
• Exterior elevations
• Core architectural details required to price and permit the build

Still required for permitting (site-specific):
Every property is different, so you’ll still need items like a site plan, utilities/connection details, and completed permit paperwork based on your jurisdiction’s requirements. We can help you identify what’s needed for your lot and coordinate the next steps.

Exclusions

Not in the package price: permit fees, utility and connection fees (sewer, water, power), and sales tax. Site conditions a desk can’t see — slope, soils, tree protection, a long sewer run — can change the price after the site visit. Renderings may show options that aren’t in the standard package; the written scope for your project is what counts.