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The Horizon – 981 sq ft.

One-bedroom ADU over a garage

IA smart, space-maximizing detached ADU built above a garage—designed to give you full-size living without sacrificing parking or storage. The main home lives on the second floor with an open kitchen, dining, and family room layout, plus a true bedroom, full bath, and a walk-in closet.

With outdoor space built in—including a balcony and main-level deck—The Horizon is a strong fit for long-term rental income, guest living, or multigenerational use when you want privacy, separation, and a more “home-like” feel.

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

  • 981 sq ft / 1 Bedroom / 1 Bathroom with a true “full home” feel
  • Garage + ADU design that preserves parking/storage while adding livable space
  • Second-floor living with an open family room, kitchen, and dining layout
  • Walk-in closet (WIC) and a well-sized primary bedroom
  • Balcony for extra light, airflow, and outdoor living
  • Large main-level deck area—great for entertaining or private outdoor space
  • Natural zoning between entry/garage level and living level for privacy

What’s Included in the Seattle DADU plan set?

This plan set provides the core drawings needed to define the layout, exterior design, and overall construction intent so you can move forward with planning, pricing, and permitting.

Typically included:

  • Floor plan layout(s) and dimensions
  • Exterior elevations
  • Core architectural details needed to price and permit the build

Still required for permitting (site-specific):
You’ll still need a site plan, utilities/connection details, and completed permit paperwork based on your jurisdiction’s requirements. We can help 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.

The Horizon – 981 sq ft.

Package details

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Project type
Standard
Size
Large ADU (981 sq ft)
No. of rooms
1
No. of baths
1 BA
ADU type
Contemporary
Notable
Over a garage
Location (state)
Washington
Structure
This ADU includes a complete, code-compliant structural shell: engineered floor and roof systems, all interior and exterior framing, required structural hardware, and full OSB wall sheathing installed to current building standards.
Included in the quote to support permitting and construction requirements. Final plans and engineering scope may vary based on site conditions, jurisdiction, and project-specific needs.
Hardie 7-1/4″ smooth lap siding with 5/4″ x 4″ trim at openings and open soffits.
Black asphalt shingle roof installation (per selection) with 15-year warranty.
Prime Windows – Series 9000.
6’8″ insulated fiberglass exterior door with partial glass, prepped for handle + deadbolt (black factory-finished).
PEX supply and ABS drain rough-in, plus one exterior cold-water hose bib located outside the bathroom.
One (1) mini-split system serving two (2) zones, kitchen and bathroom exhaust ventilation, and one (1) in-wall electric heater in the bathroom.
125A or 200A service (as available from the main home), standard wiring/outlets, and code-required AFCI/GFCI protection.
Eight (8) recessed lights, two (2) wall-mounted fixtures, and three (3) ceiling-mounted fixtures.
Fiberglass insulation meeting the current Washington State Energy Code (2025). Optional upgrade: AeroSeal (if requested).
Code-compliant drywall installation with light-to-medium orange peel texture and square corner bead throughout.
Hollow-core 1- or 2-panel interior doors with standard casing, base, and window sills.
Craftsman-style cabinetry with color selection from United Signature showroom samples.
Kingmore Plumbing builder selections (Marcato line for faucets), standard single-control shower system, and appliances per United Signature design package.
LVP throughout (showroom selection). If applicable: main level/stairs LVP and second-floor carpet.
Up to three (3) exterior colors, one (1) neutral interior wall/ceiling color, and white millwork + interior doors.
Wire shelving: four (4) rows in pantry, one (1) row in closet, and one (1) shelf above washer/dryer.
Final grading and cleanup to meet code within five (5) feet of the foundation perimeter.

How DADU will look like

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NOTE: Permitting can take several months — secure your spot now to be ready for 2026 builds.

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