7 county-level rules, plus city-specific rules for 2 cities in Boulder County, Colorado.
Verified from official government sources
In unincorporated Boulder County, fences 6 feet high or under (measured from existing grade) need no building permit. Fences over 6 feet require a permit and must meet the zoning district's setbacks. Fences of any height in a floodplain need a permit.
Boulder County Land Use Dept. Publication P/28, Fence Requirements
Building Permits are not required for fences 6 feet in height and under from existing grade (i.e., not on a berm or platform). However, fences of any height in the floodplain require a permit.
A building permit is required to build a fence over 6 feet high in unincorporated Boulder County, and for a fence of any height inside a 100-year floodplain. Over-6-foot fences must meet zoning setbacks and may need engineered footing plans.
Boulder County Land Use Dept. Publication P/28, Fence Requirements
Fences over 6 feet in height require a building permit for construction, and must meet setback requirements for the zoning district in which they are located. Fences over 6 feet may require plans for the footings and foundation that are prepared and stamped by a professional engineer.
Boulder County requires all fence components, including footings, to sit on the fence owner's own property, and bans fences from the road right-of-way. The county does not enforce private boundary disputes or subdivision covenants between neighbors.
Boulder County Land Use Dept. Publication P/28, Fence Requirements
All fence components, including footings, must be on the fence owner's property. Fences are not allowed within the road right-of-way.
In unincorporated Boulder County a retaining wall over 48 inches (4 feet), measured from bottom of footing to top, requires a building permit. Retaining walls are not counted as fences and must meet International Building Code structural design standards.
Boulder County Land Use Dept. Publication P/28, Fence Requirements
The term fence does not include retaining walls. Also, fences built around a developed use... must meet other zoning, land use, and Building Code standards. Retaining walls and masonry fences must meet the structural design standards of the International Building Code.
Boulder County fences must sit entirely on the owner's property, stay out of the road right-of-way, and not interfere with the sight triangle at intersections. Floodplain fences need a Floodplain Development Permit and specific open-fence designs.
Boulder County Land Use Dept. Publication P/28, Fence Requirements
Fences of any height can not interfere with the sight triangle at intersections. The sight triangle varies based on the posted speed of the road.
Boulder County sets no general material palette for standard fences in the unincorporated area, but floodplain fences must use approved open designs, and masonry fences must meet International Building Code structural standards. Wildlife-safe materials may be required by Land Use approval.
Boulder County Land Use Dept. Publication P/28, Fence Requirements
Retaining walls and masonry fences must meet the structural design standards of the International Building Code.
Standard fences in unincorporated Boulder County have no county-mandated material palette, but floodplain and masonry fences do. Floodplain fences must follow open-design specs; masonry fences and retaining walls must meet International Building Code standards.
Boulder County Land Use Dept. Publication P/28, Standards for Fencing in a Floodplain
Open barbed or barbless wire fencing shall have no more than one horizontal strand per foot of height and no more than one vertical wire or post every six feet.
2 cities in Boulder County have their own fence regulations rules. Each link goes to that city's dedicated page with code citations.
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