Bellingham, WA Accessory Structures: Carport Rules (2026)

Carports in Bellingham are accessory structures governed primarily by BMC 20.30.100 (Accessory Buildings and Uses) in RS zones. Detached carports follow accessory-building rules: max one story or 12 ft height under either BMC 20.08.020 height definition; max 800 sq ft area (larger only by conditional use permit); located in the rear yard or rear 22 ft of an interior side yard; not used for human habitation or business; not constructed before the main building. Side and rear setbacks for detached accessory structures are typically 5 ft per BMC 20.30.040 / 20.10.080. Attached carports follow the principal-building setbacks of the underlying zone — typical RS standards under BMC 20.30.040 include a 20-25 ft front yard, 5-7 ft side yards, and 20-25 ft rear yard (exact values vary by neighborhood plan and zoning designation per BMC 20.00 zoning tables). Maximum height for the principal building (and attached carport) is 35 ft under BMC 20.08.020 height definition 1 or 20 ft under definition 2. Construction requires a building permit from the Bellingham Permit Center (210 Lottie Street, 360-778-8300) under the 2018 Washington State Building Code (RCW 19.27 + WAC 51-50). Required design checks include engineered post and roof framing, anchorage to footings to resist Bellingham basic wind speed (~85-95 mph per WAC 51-50 with localized exposure conditions on Chuckanut and Squalicum bluffs and waterfront), Seismic Design Category D2 lateral forces (higher than central/eastern WA due to Cascadia Subduction Zone proximity), and snow load per WAC 51-50 (typically 25-30 psf in Bellingham, higher at elevation on Galbraith Mountain or Sehome Hill). Permit fees per BMC 14.32.020. Permanently enclosing a carport with walls is a structural alteration converting it from IRC Group U-occupancy carport to Group U garage — triggering a new building permit, fire-separation between the new garage and any habitable interior (1/2 inch gypsum board per IRC R302.6), an overhead garage door or equivalent, vehicle barrier curbs, and a code-compliant slab. Further enclosing a carport-turned-garage with full HVAC and habitable use is a separate change of occupancy to R-3 — see garage-conversions subcategory. Manufactured carport kits (steel-frame, fabric-cover) sold at home centers still require a building permit unless they qualify as a temporary structure under WAC 51-50 (typically 180 days). Bellingham's wind and seismic conditions exceed the design specs of many off-the-shelf carport kits without engineered ground-anchor upgrades.