What kind of fence posts do you need?
Fence posts come in many shapes and sizes, and are made from a variety of materials. Steel T posts are popular for their price and the low equipment costs required to use them. As most of you know, the amount of steel in farm store T posts has steadily decreased over the years, resulting in a product that won’t last very long. Heavy T posts are still available, but have become cost-prohibitive compared to the other options available. In situations where equipment access is limited, and ground conditions are less than desirable, T posts can be the best option.
Wood posts can be made from several types of wood, but the most common are Southern Yellow Pine (SYP) in the south and Red Pine in the north. Of course, Hedge, Cedar, Sassafras, Locust, Lodgepole Pine and many others are still used where they are available, but for now, we will stick with what is commercially available in the Midwest.
We prefer SYP over Red Pine because it is typically stronger. Red Pine has concentric knots, which can make for a nice place for a post to snap. Knots and heartwood also won’t take any treatment, so all those knots can be a place for rot or insects to get started.
SYP can be treated with several different chemicals, and by several different methods. The most common today is pressure-treated Chromated Copper Arsenate, or CCA. The process starts with a post that is near 18-20% moisture. Bundles of posts will be loaded into a vacuum chamber, and as the chamber is pumped down to vacuum pressure, the cells of the SYP will compress as the air is pulled from them. Once vacuum is achieved, the treatment solution is introduced under pressure, and the rapid swelling of the cells draws in the CCA treatment. The rate of treatment with typical agricultural use fence posts is .4 lbs of CCA per cubic foot of wood. Rates of up to .6 lbs per cu ft are available, but will be special order.
Our favorite treatment for SYP posts is creosote. It is commonly thought that creosote was outlawed, but that is not the case. The creosote pressure treatment process is similar to the CCA process, with a few minor differences. Heated coal tar creosote will be introduced under pressure instead of CCA, and SYP will generally take 6-8 lbs per cu ft of creosote. Creosote post are quite a bit heavier than their CCA counterparts. Care should be taken when handling both CCA and creosote to avoid skin, eye, and lung contact. We recommend long sleeves, gloves, and eye protection when handling, and a face shield and mask when cutting or drilling.
Steel pipe can be a good alternative to timber posts, but can require cutting and welding to install, as well as painting to prevent rust in wetter areas of the country. Used oilfield pipe and seconds or blemished new stock are readily available in many areas.
Fiberglass posts are becoming more common, but care should be taken to select a proper product. Fiberglass that isn’t UV stabilized will photo degrade or “rot” in the sun. Some fiberglass will conduct small amounts of electricity, so care should be taken when building an electric fence. Hot wires will still generally need to be on an insulator to have an efficient fence. This is why it can take such a large energizer to electrify even the smallest of hot wire on fiberglass posts fences.