Cowlitz County, WA Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in Cowlitz County, WA, also referred to as storage shed, backyard shed, or accessory building regulations, set size limits, setbacks, and when a building permit is required.
Key Facts
- Permit exempt size
- 120 sq ft (200 sq ft for 1-2 family homes)
- Rear setback
- 5 ft minimum, § 18.10.514
- Exempt fence height
- up to 7 ft, § 16.05.090
- Building code penalty
- up to $250 fine/90 days, § 1.01.090
- Setback civil penalty
- $1,000 per violation, § 2.06.080
Summary
A detached storage shed or playhouse in unincorporated Cowlitz County does not need a building permit if it is one story and no larger than 120 square feet, or 200 square feet when accessory to a one- or two-family home, under Cowlitz County Code § 16.05.090, and it must still sit at least 5 feet from the rear lot line under § 18.10.514.
Section 106.3, Work exempt from permit, is revised as follows: 1. One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses, provided the floor area does not exceed 120 square feet (200 square feet if accessory to a one and two-family dwelling). ... The rear yard setback for any detached residential accessory structure shall be a minimum of five feet from the rear lot line.
Full Breakdown
Cowlitz County Code § 16.05.090 adopts the 2021 International Wildland-Urban Interface Code and revises its Section 106.3, Work Exempt from Permit, to list one-story detached accessory structures used as tool and storage sheds, playhouses and similar uses as exempt from a building permit, provided the floor area does not exceed 120 square feet, a threshold that rises to 200 square feet if the shed is accessory to a one- and two-family dwelling. Fences up to 7 feet high are exempt under the same revised section.
Even permit-exempt sheds must still meet the county's zoning setbacks: § 18.10.514, titled Rear Yard Setback Exemptions, Accessory Buildings, sets the rear yard setback for any detached residential accessory structure at a minimum of 5 feet from the rear lot line, a reduction from the district's standard rear setback under Table 18.10.501 (15 feet in most residential districts). A shed that exceeds the 120- or 200-square-foot threshold loses the permit exemption and needs a building permit through the Building and Planning Department, and any accessory structure sited within 200 feet of a residence on a separate lot in the AG-I zone also triggers the 10-foot side and 15-foot rear setback at § 18.10.516.
The county's general front yard rule at § 18.10.505 continues to apply to accessory structures placed in a front yard, since § 18.10.514 addresses only the rear setback.
Violations & Fines
Building a shed larger than the 120- or 200-square-foot permit-exempt threshold without a building permit is a misdemeanor under the county's general penalty, CCC § 1.01.090, punishable by a fine of up to $250, up to 90 days in jail, or both. Placing any accessory structure closer than 5 feet to the rear lot line, permitted or not, is a Land Use Ordinance violation under § 2.06.040, carrying a $1,000 civil penalty per violation under § 2.06.080.
Frequently Asked Questions
Do I need a permit for a backyard storage shed in Cowlitz County?
How close to my back property line can I place a shed?
What if my shed is bigger than 200 square feet?
Sources & Official References
Other rules in Cowlitz County
Compare Cowlitz County to another location·View the Washington accessory structures overview
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