Compare ADU zoning rules across 5 Washington cities. Average ADU score: 7.6/10.
| City | Max Size | Setbacks | Permit Fees | Build Cost | 1BR Rent | Score |
|---|---|---|---|---|---|---|
| Bellevue | 1,200 sq ft (Director may approve more for single-floor units in the primary structure or conversions/additions to existing accessory structures) | Subject to middle-housing dimensional standards (LUC 20.20.538) — Confirm with Bellevue Development Services | Permit and plan review fees based on project valuation — Confirm with Bellevue Development Services | $180,000-$380,000 | $2,500-$2,900/mo | 8/10 |
| Seattle | 1,000 sq ft of floor area above grade (size also constrained by FAR and lot coverage) | 5 feet | $2,000-$5,000+ in SDCI permit fees (varies with valuation; hourly review rates apply) | $160,000-$320,000 | $1,600-$2,100/mo | 9/10 |
| Spokane | 1,000 sq ft | Confirm with Spokane Planning (SMC Title 17C) | $2,000-$3,500 | $110,000-$220,000 | $1,000-$1,450/mo | 6/10 |
| Tacoma | 1,000 sq ft living area | 15 feet (no setback required from an alley) | $1,800-$2,800 | $135,000-$270,000 | $1,300-$1,750/mo | 8/10 |
| Vancouver | 1,000 sq ft gross floor area | Confirm with Vancouver Planning (VMC 20.810.040) | $1,900-$3,200 | $135,000-$270,000 | $1,250-$1,700/mo | 7/10 |
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