King County, WA Short-Term Rentals: Occupancy Limits (2026)

King County does not have a standalone occupancy cap for short-term rentals in unincorporated areas. Instead, occupancy is governed by the Washington State Building Code adopted in KCC 16.04 and the International Residential Code and International Property Maintenance Code standards, which control sleeping room size, ceiling height, and egress. A bedroom must generally be at least 70 square feet, with a minimum dimension of 7 feet in any direction, a closable door, and at least one emergency escape and rescue opening (window or door) meeting minimum size standards for egress. A common industry rule of thumb used by hosts is two guests per bedroom plus two additional guests, though this is not a specific county code. Hosts must ensure the total number of occupants does not exceed what the home safely accommodates — for example, sleeping guests in living rooms or converted garages that lack emergency egress may violate building code. Septic systems on properties not connected to sewer (common in rural unincorporated King County) have design capacities based on bedroom count, and exceeding those can strain the system and violate Public Health Seattle and King County septic rules. Incorporated cities within King County, particularly Seattle, have specific occupancy caps for STRs that differ from unincorporated county standards.