Fences are exempt from building permits if they are under 7 feet high and not on shoreline (or in an area with critical areas). This information can be found on the 2nd page of Brochure #30: Single Family Residence: https://www.co.jefferson.wa.us/DocumentCenter/View/627/Single-Family-Residence-PDF?bidId=
Fences cannot be built within the County right-of-way. If the property line is close to a road, Public Works would most likely require the clear zone be met as we do for utility structures (poles, vaults, etc.). For example, on a 25 mph road, the setback would be 10 feet from the edge of pavement. Additionally, a fence cannot block site distance. Setback information can be found here: https://www.co.jefferson.wa.us/DocumentCenter/View/618/Residential-Setbacks-PDF?bidId=
A fence, no matter what the material, is still a fence over seven feet. For example, a barbed wire fence in a pasture that is 5' high and all barbed wire and posts is still a fence. The intent of the code though is concerned with the fence over 7' high becoming a sail or just falling over and causing more damage than a 5' high fence made of the same material.