Some counties welcome barndominiums, but metro and suburban areas may restrict them.
The WA State Building Code Council adopts state codes. Local jurisdictions enforce them. Cities and counties may adopt more restrictive amendments.
Primary Code
Washington State Building Code
Code Version
2021 IBC / 2021 IRC with WA amendments
Adoption Level
Statewide
Statewide Enforcement
Yes
Seattle and Puget Sound area have longer timelines. Eastern WA is faster.
Residential
Required
Commercial
Required
Agricultural
Not Required
Size threshold: structures under 200 sq ft may be exempt.
Agricultural buildings may be exempt from building permits under certain conditions. Buildings must be on agricultural land and used exclusively for farming.
Accessory structures under 200 sq ft typically exempt.
Cascadia Subduction Zone creates significant seismic risk in western WA. Mountain areas have extreme snow loads. Coastal wind exposure in some areas.
Wind Load
95–130 mph
moderate zone
Snow Load
15–150+ psf
Seismic
B–D
Category
Flood
FEMA Regulated
Energy Code
WA State Energy Code
Version
2021 WA Energy Code
Washington has its own energy code that exceeds the base IECC.
License Type
WA Department of Labor & Industries registration
Washington requires all contractors to register with L&I. General contractor, specialty, and residential contractor types.
Front
20–30 ft
Side
5–10 ft
Rear
15–20 ft
Varies by jurisdiction. Shoreline Management Act setbacks near waterways.
Seismic foundation design critical in western WA. Sandy and glacial soils vary across the state.
Standard permitting. Seismic design in western WA.
Agricultural exemptions available for farm buildings.
Limited in western WA. Eastern Washington and rural areas more viable.
Standard permits required.
Full state building code compliance.
HOAs common in Puget Sound area suburbs. Eastern Washington and rural areas more unrestricted.
Flood zones along Puget Sound, Columbia River, and other waterways.
Verify the information above directly from these official sources. Regulations change — always confirm with your local building department before starting construction.
Disclaimer: This guide is for informational purposes only and does not constitute legal or professional advice. Building codes, permit requirements, and zoning regulations change frequently. Always verify current requirements with your local building department, planning office, or a licensed professional before starting construction. Homestead Steel Structures & Design is not a legal authority on building codes or zoning regulations. Last updated February 2026.
