How Much Does It Cost to Build an ADU in Vancouver, WA?

In Vancouver, WA, a detached ADU (accessory dwelling unit) typically costs $180,000–$350,000, and an attached ADU or garage conversion runs $120,000–$250,000. Final cost depends on square footage, finish level, whether you're building over an existing garage, and site conditions like utility runs and grading. As of 2026, the average detached 600-800 sq ft ADU in Clark County is running around $250,000–$300,000 all-in, including design, permitting, construction, and utility connections.

What Drives ADU Cost in Vancouver

ADU pricing varies dramatically based on five factors:

1. Size (biggest driver). Vancouver ADUs typically range from 400 to 1,000 square feet. Cost per square foot doesn't scale linearly — smaller ADUs cost more per square foot because you still need a full kitchen, bathroom, and utility connections regardless of size.

2. Detached vs attached vs garage conversion:

• Detached ADU (new construction): Highest cost, most flexibility. $180,000–$350,000+.

• Attached ADU (addition): Mid-range cost. $150,000–$300,000. Requires cutting into existing house.

• Garage conversion: Lowest cost. $80,000–$180,000. Limited by existing footprint and utilities.

3. Finish level. Standard finishes (LVP flooring, laminate counters, builder-grade appliances) sit at the low end. Premium finishes (hardwood, quartz, high-end appliances) push you toward the top of the range.

4. Utility connections. If your existing sewer, water, and electrical service can handle an ADU without upgrades, you save $10,000–$30,000. If your service panel needs upgrading, or if a new sewer connection is required, add $15,000–$40,000.

5. Site conditions. Flat, buildable lots cost less. Sloped lots requiring engineered foundations, drainage systems, or extensive tree work add cost.

Typical Vancouver ADU Cost Breakdown

For a 700 sq ft detached ADU at $280,000 total, expect:

• Design and permitting: $12,000–$20,000

• Site prep, foundation: $30,000–$50,000

• Framing, roof, siding, windows: $60,000–$85,000

• Plumbing, electrical, HVAC: $40,000–$55,000

• Interior finishes (flooring, drywall, paint, trim): $30,000–$45,000

• Kitchen and bath (cabinets, counters, fixtures, appliances): $25,000–$45,000

• Utility connections: $10,000–$30,000

• Landscaping, pathways, final grading: $5,000–$15,000

Vancouver ADU Permitting

Vancouver's ADU zoning is homeowner-friendly. Most residential lots allow at least one ADU. Common requirements:

• Setback minimums (typically 5 feet from property lines)

• Maximum size (typically 800 sq ft or 75% of primary home)

• Parking (sometimes waived, depends on lot)

• Height limits

• One entrance not facing the primary home's main entrance (some cases)

We handle all permitting through the City of Vancouver Community Development or Clark County (for unincorporated areas).

Is an ADU Worth It in Vancouver?

For many Vancouver homeowners, yes. Common reasons:

• Rental income ($1,500–$2,500/month in current Vancouver market)

• Aging parents — housing family while preserving independence

• Adult children — housing kids returning after college

• Home value — ADUs typically add $150,000–$300,000+ to appraised value

• Short-term rental (where allowed) — higher income but more management

Why Vancouver Homeowners Choose IVY Contracting for ADUs

We build ADUs across Vancouver and Clark County — attached, detached, and garage conversions. Every ADU project includes 3D visual renderings so you see the finished unit before we break ground. Tim personally manages every ADU project from design through utility inspection.

Learn more about our Vancouver ADU services →