ADUs at Snoqualmie Pass

Snoqualmie Pass has two chronic housing problems at once. Summit at Snoqualmie and the businesses around it need places for seasonal staff to live within driving distance of the lifts, and visitors coming up for a weekend on the hill need somewhere to sleep that isn't a two-hour round trip from Seattle or Cle Elum. A second legal dwelling on your lot answers both — and you get to choose which one, season by season.

The construction math is what makes it compelling. When the ADU is designed into the primary house from day one, it shares the hardest and most expensive parts of a mountain build: one excavation, one foundation, one roof structure, one driveway to plow, one water and septic or utility connection, one crew mobilization to a site with a short building season. A separate detached structure duplicates most of that. Attaching it means the incremental cost per square foot of the rental space is typically well below the cost per square foot of the house it's attached to.

On the income side you have real optionality. A seasonal lease to ski-area employees runs quiet and predictable through the winter with one tenant relationship to manage. Nightly rental to visitors chases the peaks — powder weekends, holidays, summer hiking and Gold Creek traffic — with higher gross and higher effort. Many owners do both: a winter lease and summer nightly bookings, or a lock-off suite they occupy themselves on the weekends they want the mountain.

None of this works as an afterthought. The ADU needs its own entry that stays usable in deep snow, its own parking that can actually be cleared, sound separation from the main living areas, and a door that can be locked off cleanly. Those are design decisions, made early and cheaply, or expensive retrofits later.

Snoqualmie Pass on the east side of the summit — Hyak, Gold Creek, Snoqualmie Pass proper — is unincorporated Kittitas County, so county zoning governs. Kittitas County defines an accessory dwelling unit as a self-contained secondary residential unit on the same lot as the primary dwelling, providing independent living facilities for one household, and it may be attached to the primary residence or detached (KCC 17.08.022).

For an ADU outside an urban growth area, the county reviews it as an administrative use permit through Community Development Services. The standards the application asks you to confirm include:

Fifteen hundred square feet is generous for a rental unit at the Pass — it is roughly the size of an entire small mountain cabin, and more than most nightly-rental guests need. The practical question is usually not how to reach the cap but where to stop. A one-bedroom in the 500–700 square foot range rents easily and costs least to build; a two-bedroom with a bunk room widens the guest pool to families and small groups; going near the cap starts to compete with the primary house for the best views and the best solar orientation.

What matters more than the number is how the square footage is arranged. Getting a full-height entry that isn't buried by roof shed, a mudroom that can take wet gear for six people, a kitchen that works for a week-long stay, and a wall assembly that keeps the main house quiet — those determine whether the unit rents well, not the raw area.

Fees, review timelines, zoning specifics and short-term rental regulations change. Confirm current ADU standards, permit fees and any short-term rental licensing requirements directly with Kittitas County Community Development Services before you commit to a plan, and check any private covenants or HOA rules on your lot — those often restrict rentals more tightly than the county does.

The Cascade House at Hyak is a Terralite Design custom home built for exactly this terrain: dark-stained siding, steep sheltering roof forms, glass aimed at the view, and volumes broken apart so the massing can absorb a secondary entry and covered outdoor space without looking like an addition. It is a useful reference for how an attached second dwelling can be folded into a Pass home rather than bolted onto it.

Where an attached unit doesn't fit the lot, Terralite Design also develops modular and prefabricated ADU and DADU designs that can be deployed to a site with far less time spent building in the weather. On a mountain lot with a short construction season, moving work off-site is worth real money. See the modular ADU/DADU work at Terralite Design.