Novice and experienced farmers are embarking on the timeless spring tradition of building fence for various livestock enterprises. If you want to have any longevity to a fence, start with the proper construction of the foundational end and corner assemblies. Follow Canadian contractor and television host Mike Holmes’s advice and “Make it Right.”
Because fence manufacturers sell a variety of fence systems and components which provide physical and/or psychological (electric) barriers to control livestock, consult with the company on construction specifications before you start.
Generally, the Northeast livestock scene is home to high tensile smooth wire or woven wire fences, barbed wire fences and wooden fences to keep animals contained. Fences that are “pulled” tight require special attention at termination ends or corner points so the fence does its job for years without constant maintenance. Typically, construction of these braced posts should never be compromised in quality.
As a way to ease into this topic, there are countless YouTube videos, fencing websites, DVDs and NRCS specification manuals that show you how to build a proper fence brace and what components to use. Fortunately for me, I trained over 30 years ago at a Kiwi fence school under the “Sensei of Fence Building,” John Wall, where I learned my lifetime craft. I left with the fence bible, “How to Build Fences with Max-Ten Wire,” which is still available and updated at Kencove Farm Fence.
The signature “H-brace” assembly starts with the right posts, which are typically treated southern yellow pine, five to seven inches in diameter by seven to eight feet long, depending on application. The reason for these traditionally used posts is their branches are offset, they are uniform, they take CCA treatment well and they have been documented as strong.
Red and Jack pine posts are also used; however, their branches grow in a ring, creating a knot point to break under pressure, so you must use bigger diameter posts to get the same strength as southern yellow.
Locust is a great post material, if you can get them in the sizes you want and they are generally straight enough to work with. Cedar is a fine alternative but must be sized up because it’s less dense and it rots over time like most wood products, treated or not.
Farmers also used railroad ties, telephone poles, plastic wood, steel posts and even “gabion basket” stone posts. Trees are in play on some farms but must be sheathed to protect them from harm. I’m not a fan of 4x4s or landscape timbers for posts because they aren’t bona fide trees and lack strength because of the milling process and the lack of treatment they generally receive because of their sapwood-to-heartwood ratio.
Getting the post in the ground brings back a memorable quote: “Animals dig holes, people drive posts.” Technological advances in hydraulic post drivers makes putting in posts to the proper depth a lot easier than using an auger, clam-shell post digger, shovel or hop bar. A pounded post is significantly stronger with less effort but is more expensive to buy; you’ll need to hire a fence company or rent a post driver, and it takes time to operate one safely and efficiently.
If you drive a post, it better be a good one because at over 100,000 psi hitting power, bad things can happen in a hurry.
Since I built fence with my grandfathers and father, I’m very familiar with using cedar posts, a hop bar and a sledgehammer to construct brace assemblies using the “Armstrong” method. However, I learned the hard way – their bracing geometry led to post lifting and fence failures. It all came down to the brace rail, either diagonal or horizontal, being too short and creating a steep lever action that helped lift the big posts out of the ground when under pull tension. Combine this with a steep pitched brace wire and you have a poor brace.
This from the British Columbia Fencing Factsheet: “The “steeper” the angle of the brace wire, the greater this vertical pull-out force. This is why short span braces (with “steeply” angled brace wire) may fail at low fence loads by end post pullout. Longer span braces (with “lower” angled brace wires) apply more horizontal load to the soil and post, failing at higher loads. Longer span braces will use the full load bearing capacities of both the soil and the post. This added strength can also be achieved by lowering the horizontal rail and therefore the brace wire angle.”
Generally, an angle of 30% or less is recommended with double-wrapped high tensile wire.
The brace rail is a major component in an H-brace system. This rail, typically eight to 10 feet long, needs to be of appropriate size (four to five inches in diameter) and strength because the compression friction is immense and can bow the post over time. As it ages, it can develop weather checks where water freezing and thawing can diminish its strength capacity. Landscape timbers and 4x4s are definite no-nos for this application.
Most information on fence brace construction will reference building a perfect eight-foot H-brace assembly as the standard. But when are the conditions really perfect when you farm in the Northeast?
My recommendation is always honor geometry and have longer brace rails on hand to lower the “lift angle” when you may not be able to get the posts in the ground as is recommended.
Another construction tip is to attend a fence training taught by an experienced professional, mentor with a fence contractor for a few days or call your friendly local Soil & Water Conservation District or NRCS staff member for help and guidance.
(West Virginia University Extension has an excellent high-tensile fence building manual at High-Tensile Wire Fencing.)
by Troy Bishopp
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