Long-term vs. short-term rental ADU in Seattle
Seattle FAS short-term rental rules, the math vs. long-term tenancy, and what we see actually working.
What Seattle's STR rules actually say
Seattle requires a Short-Term Rental Operator License plus a Regulatory License for each unit. STR operators are limited to two properties: one primary residence and one additional unit. The City defines short-term as fewer than 30 consecutive nights.
An ADU on the same parcel as your primary residence qualifies as one of the two allowable units.
Sources:City of Seattle
Gross-revenue comparison
Long-term DADU rent (per our 2024 ledger): median $2,650/month, $31,800/year, 12-day average vacancy.
Short-term DADU revenue on the same units (if STR were elected): $4,800–$6,200/month gross, but 30–40% to operating costs (cleaning, supplies, software, utility increases) and ~10–15% vacancy in shoulder months.
Net STR yield runs 25–45% higher than long-term, but with materially more management workload.
Sources:Zillow Research
What we see actually working
Long-term tenancy for owners optimizing for hands-off cash flow. Short-term for owners who genuinely enjoy hospitality work or already operate vacation rentals. Mid-term (30–180 day stays for traveling nurses, relocators, insurance-displacement renters) increasingly the default — it captures 80% of STR revenue with 30% of the workload and skirts the STR licensing cap.
Sources:Sightline Institute
