Taken from "Fences for Horses" by G. T. Roberson & R. A. Mowrey
There are many options in fencing material available to the owner. The most common materials are wood, metal, plastic, wire and concrete. Some fencing systems combine more than one of these materials. Examine the pros and cons of all materials before making a choice.
Wood is one of the most popular materials available for horse fences. Wood can be used for posts, braces, boards or rails. Wood will naturally decay when exposed to ground contact or weather, therefore pressure treated or naturally decay-resistant species, such as cypress, black locust or red cedar, should be used. Preservative treatments such as creosote, pentachlorophenol and inorganic arsenic such as chromated copper asrsenate (CCA) are available to retard decay. CCA treated wood products are being phased out for residential uses but may still be available for agricultural applications such as fence posts, boards and rails. New treatment compounds to replace CCA are being evaluated. Wood treated with creosote or pentachlorophenol should not be used in the interiors of farm buildings where there may be direct contact with horses that may bite or lick the wood. Treated wood of any type should not be used in an application where it will be in direct contact with feed, hay or drinking water.
Metal can be used for posts, rails, wire, and as hardware to secure other fencing materials. Steel is the preferred material due to its strength and durability. Steel used for posts or rails should be galvanized to prevent rust or painted with an appropriate coating. Steel used for fasteners such as nails, staples or screws should be galvanized for rust prevention. Stainless steel fasteners can be used if needed for added corrosion protection but are more expensive. Wire fencing is typically galvanized steel, but some stainless steel and aluminum is used as well. Galvanized steel wire is used because it offers good strength and corrosion resistance at a reasonable cost.
Plastic used for fencing should be weather resistant and sunlight stabilized. Polyethylene (PE), polyvinyl chloride (PVC) and fiberglass are the most common materials. Plastic tends to become brittle as it gets cold and may soften if it gets extremely hot. Plastic used for fencing should be formulated to resist these extremes. Some plastic fencing is intended for residential application only. This type of fencing uses thinner material and is not suitable to contain horses. Be sure to select fencing designed for farm or horse fencing. If in doubt, request test data from the manufacturer for fence materials that you are considering.
Plastic-coated wood is also available for fencing. Pressure-treated wood is enclosed in polyvinyl chloride (PVC) or polyethylene (PE) to provide weather resistance. This product combines the strength of wood with the durability and low maintenance of plastic.
Plastic-coated wire is another popular choice. Galvanized wire is coated with plastic to improve visibility for the horse. This wire can be single strand or wire rail. The wire rail design uses two or three strands of wire, laid side by side and spaced 1 to 5 inches apart. When molded with the polymer, it forms a thin fencing strip or rail that is strong and flexible, yet wide enough to be visible.
Concrete can be used for posts, rails, or to secure other types of posts in the ground. When used for posts and rails, it is reinforced with steel bars. Concrete is strong and durable but expensive if used as a complete fence. Minimum strength requirements for concrete should be 4,000 pounds per square inch (PSI).