Editor’s note: This is the first part of a two-part series on building and maintaining fences. Part II will run on Aug. 14.
Keeping fences in good repair not only extends their life but reduces risk of injury to livestock from protruding nails or sagging wires--and keeps them from getting out on a highway or into a neighbor’s range or pasture.
Most permanent pasture fences for cattle utilize barbed-wire, net-wire or multiple strands of high-tensile electric wire, secured to well-set posts. In some terrain, however, a jack fence (poles nailed or screwed to jack legs) is better than trying to set posts in deep mud or solid rock. Pole fences need periodic maintenance, however, to make sure poles don’t come loose, and they often need replaced; lifespan of a wood fence is 20 years or less. A properly built wire fence will last longer.
Jason Nelson ranches in southern Alberta, and does custom fencing for many ranchers in his area. He tries to build durable fences that require less maintenance, and says the key to a good barbed-wire fence is good braces. In easy terrain on straight stretches without corners, Nelson puts a brace every quarter mile—at the end of every roll of wire. “Low spots require additional braces, to make sure the tight wire doesn’t pull up the posts. Often when we go through a gully we put a brace on each side, but with some we just put 8-foot posts through the low spot,” he said. Then the main wires can go straight across, with additional wires in the low spot.
In some instances he’s had to hang an anchor in the gully, to keep the wires from pulling up the posts, but normally uses large-diameter 8-foot posts. “I also use 8-foot posts for braces so they can be set deeper, and a 12-foot angle brace (from the top of one post to the bottom of the other). These hold very well,” said Nelson.
Wire spacing—and how many wires—depends on the situation, such as how big the pasture is and how much pressure there will be on the fence, from cattle or wildlife. Post spacing can vary, as well. “With a normal 4-wire fence we usually put posts every 12 to 13 feet in range country, but in high-pressure areas some ranchers want a 5-wire fence.” Nelson uses barbed staples for attaching wires to wood posts. They stay in better and don’t pop out as readily as smooth staples.
Wood posts last longer in dry ground and dry climates, but the biggest factor in how long a post lasts is treat—to keep the wood from rotting—and the greatest risk area for rot is at ground level. Moisture is not as damaging as exposure to sunlight, oxygen, and water. This combination breaks down the wood. “Never set a post deeper than the treated portion; it should extend at least 2 or 3 inches above ground after the post is set.”
Sometimes you can adequately repair/extend the life of an old fence by setting steel posts between the wood posts that are starting to rot off. Metal posts eventually rust but last much longer than wood.
Nelson often uses posts made of sucker rod, with wire hooks welded on. “These go through rocks very well and don’t bend easily. You just set the wires in the hooks, use a pipe wrench to give the post a quarter turn, and it locks the wires into place. We often use these posts when fencing in winter when ground is frozen, because we can pound them down through frost—a lot easier than trying to set a wood post,” he explains.
“I use a piece of drill stem to hold with my post pounder and pound the small post down through the center of it. Otherwise the little posts can flex and fly out when you are pounding them.”
Metal posts also work nicely when a fence must go through wet areas where it would be difficult to drive wood posts. “I’ve done a lot of fencing through bogs, and used 7-foot T-posts. They go far enough down to hit solid ground and hold,” said Nelson.