Meets Base WA IRC R105.2 Dimensional Exemption (Subject to Local Setbacks & Site Overlays)
Unincorporated Cowlitz County Base WA IRC R105.2 Dimensional Rule:
≤ 200 sq ft floor area, single-story, detached residential storage/tool shed with no plumbing or habitable sleeping space (must still obey local 5 ft property line setbacks).
≤ 200 sq ft floor area, single-story, detached residential storage/tool shed with no plumbing or habitable sleeping space (must still obey local 5 ft property line setbacks).
Local Setback & Municipal Note (Unincorporated Cowlitz County):
≤ 200 sq ft one-story detached residential accessory structure is exempt from building permit; Critical Areas Ordinance buffers apply.
⚠️ Informational Code Reference Only — Not an Official City Determination: Even when a deck, wall, shed, or fence meets the base WA IRC R105.2 dimensional threshold, local property-line setbacks, critical-area/wetland buffers, shoreline overlays (e.g., Kalama/Columbia/Lewis rivers), steep-slope geohazard zones, utility easements, separate electrical/plumbing permits, and HOA rules still apply. The property owner and contractor of record are solely responsible for verifying parcel rules with the local permit counter before work begins.
Frequently Asked Questions (Unincorporated Cowlitz County, WA)
1. Can I build a 10x20 (200 sq ft) shed without a permit in Unincorporated Cowlitz County, WA?
Yes. Under WA IRC R105.2 as enforced by Unincorporated Cowlitz County, a one-story detached residential storage shed with a projected roof/floor area of 200 sq ft or less (such as a 10x20 or 12x16 shed) is exempt from a building permit, provided you obey property line setbacks.
2. Do permit-exempt sheds still have to follow setbacks in Unincorporated Cowlitz County, WA?
Yes! Even when a shed under 200 sq ft is exempt from a building permit, Unincorporated Cowlitz County zoning still requires keeping it out of utility easements and maintaining the required side and rear yard setback (typically 5 feet).