Can You Airbnb Your ADU in Seattle? STR Rules & the Real Math

• Seattle's STR framework generally allows an operator two units: your primary residence + one more — which is precisely the owner-occupied home + backyard DADU setup. (As of this writing; regulations change — we confirm current rules for every project.)
• Requirements to operate: a city STR operator license, a business license tax certificate, and your license number displayed on every platform listing; lodging taxes apply and platforms typically collect them.
• The honest seasonality: Seattle tourism peaks roughly May through September — the other seven months are where Airbnb spreadsheets go to die.
• Real STR costs long-term rentals don't have: furnishing the unit, cleaning and turnover every stay, supplies, utilities on you, platform fees, and either your hours or a professional co-host's meaningful cut.
• The sleeper strategy: 30+ day furnished mid-term rentals (traveling nurses, relocations, military families on temporary orders) — typically outside STR licensing, at a premium over unfurnished long-term, with a fraction of the turnover.
• Baseline to beat: a long-term DADU tenant at $1,600–$2,800/month with near-zero vacancy and no Saturday cleanings.

Seattle regulated short-term rentals years ago, and the shape of the rules is friendlier to ADU owners than to investors: the operator cap of a primary residence plus one additional unit shuts out the ten-condo Airbnb baron — but a homeowner living in the main house with a cottage out back is the exact intended user. The mechanics: get the city's STR operator license, hold a business license, put the license number on your listing, and let the platform handle lodging taxes. Two honest caveats we give every client: rules evolve (we check current requirements during your project, not from memory), and outside Seattle the rulebook changes — Tacoma, unincorporated Pierce County, and each suburb write their own; part of our feasibility work is knowing which rulebook your parcel lives under.

Peak-summer nights in a well-located Seattle ADU can gross more per month than a long-term lease — that part of the dream is real. The rest of the year is the reckoning: demand thins from fall through spring, and every booking carries costs a lease never sees — cleaning between stays, linens and restocking, utilities and Wi-Fi on you, platform fees, and the hours of messaging, or a co-host who takes a serious percentage to do it for you. Owners who've run the experiment describe the same arc: strong summer, quiet winter, and the discovery that blocking dates for personal use fights the platform's algorithm — the calendar wants to be a business, not a spare room. None of this makes Airbnb wrong; it makes it a job with seasonality, and it should be compared to the boring alternative honestly: $1,600–$2,800 a month, every month, from one tenant you screened once.

Between "hotel" and "lease" sits the option that quietly wins our clients over: furnished rentals of 30 days or longer. Traveling nurses on assignment, families mid-relocation, homeowners displaced by their own remodels, and — in our corridor — military families on temporary orders near JBLM all need exactly this product. Thirty-plus-day stays generally sit outside STR licensing, command a furnished premium over a bare long-term lease, and turn over a handful of times a year instead of every weekend. It's the flexibility of Airbnb with the sanity of a lease — and it pairs naturally with the JBLM demand we covered in our military-rental guide.

Long-term, mid-term, or STR? Check your parcel in 60 seconds, then we'll run the numbers together. Start with Analyze My Lot.

Here's the part that matters at the design table: the same well-built DADU serves all three strategies. Separate entrance and parking, durable finishes (LVP floors, quartz counters), in-unit laundry, smart lock, and a layout that photographs well — build that once and you can run long-term this year, mid-term next year, and summer STR the year your daughter's college tuition hits. What we steer clients away from is building for Airbnb specifically — themed interiors and hospitality gadgets age fast, while flexibility never does. Run your parcel through Analyze My Lot and we'll pressure-test all three income models against your actual numbers in the consultation. Weighing resale too? See does an ADU increase home value.