This article is reprinted with permission from Ag Decision Maker.
Dr. William Edwards
Iowa State University
Fencing costs are one of the most expensive aspects of livestock grazing. The type of fence constructed greatly impacts the cost per foot, total cost, and annual ownership cost. In addition, the shape of the paddocks affects the amount of materials needed and labor required for construction of the fence.
This publication compares the costs of building a quarter-mile (1,320 feet) straight perimeter fence with four different types of permanent fencing plus temporary interior fencing. These are: woven wire, barbed wire, high-tensile non-electric, high-tensile electrified and temporary interior fencing.
The type of fencing selected varies by personal choice and the species of livestock to be confined. In general all configurations shown can be used with cattle, woven wire and high-tensile electrified can be used with sheep, and woven wire can be used with hogs.
The list of materials needed for each type of fencing is from Costs of Cattle Fencing for Grazing Areas (see references at the end of the article). Costs were adjusted to 2011 prices provided by a number of Iowa retailers, although prices may vary. Labor was valued at $15.05 per hour for woven wire and $16.25 per hour for barbed wire, the average fence building custom charges reported in AgDM File A3-10, 2011 Iowa Farm Custom Rate Survey. These charges include the cost of equipment and tools for building fence, as well as labor. Gates are not included in the estimates.
Fencing can be configured in many different ways, using various types of fencing materials. The examples in this publication provide a general comparison between the following five configurations.
Woven wire fence
The woven wire fence (see Table 1) employs a brace that uses two 8-inch diameter posts and a 4-inch diameter cross-brace at each end. Posts between the braces are steel "T" posts alternated with 4-inch diameter pressure-treated wood posts. All posts are spaced 12 feet apart with one strand of barbed wire at the top.
Barbed wire fence
Materials for the barbed wire fence (see Table 2) are similar to the woven wire fence except that five strands of 12-gauge barbed wire are substituted for the woven wire and single strand of barbed wire.
High-tensile non-electric wire fence
The high tensile non-electric fence (see Table 3) uses eight strands of 12.5-gauge high-tensile wire on 4-inch diameter pressure-treated wood posts. Posts are 20 feet apart. Bracing uses three 8-inch diameter posts and two 4-inch diameter cross braces on each end. Wire tension on this fence is maintained with springs and ratchet-type tensioning devices.
An alternative is to set posts 30 feet apart and place two stay rods in the wire between each set of posts. Cost would be reduced about $85 for every 1,320 feet of fence, or $0.064 per foot.
High-tensile electrified wire fence
The high tensile electrified fence (see Table 4) uses five strands of 12.5 gauge high tensile wire with three charged and two grounded wires. Bracing uses three 8-inch diameter posts and two 4-inch diameter cross braces on each end. With the exception of brace posts, steel “T” posts spaced 25 feet apart are used. One quarter of the cost of an electric energizer is included in the cost of the 1,320 foot fence, assuming that such a unit would be used to energize at least a mile of fence. Wire tension on this fence is maintained with springs and ratchet type tensioning devises.
Electrified polywire fence (for interior use only)
The polywire fence (see Table 5) uses one strand of polywire. With the exception of the end posts, fiberglass rod posts are used and spaced 40 feet apart. One-fourth of the cost of an electric energizer is included in the cost of 1,320 feet of fence, assuming that such a unit would be used to energize at least a mile of fence.
If substituting polytape for polywire, the total will increase by about $40 because polytape costs about twice as much as polywire. If substituting high-tensile wire for polywire, the cost will increase by about $125-$150 (change includes switching to five-eighths inch diameter fiberglass posts)
Estimating annual ownership costs
Annual ownership costs for each type of fence are shown in Table 6. In addition to the initial material, labor and construction costs, owners need to determine depreciation and maintenance costs required over the useful life of the fencing.
Ownership costs for polywire and polytape are more difficult to estimate than for other types of fencing. The non-wire/tape components have an estimated life of 25 years; the polywire and polytape will likely last about four to five years. Based on these estimates, the annual ownership cost for a polywire or polytape fence is approximately $0.06-$0.07 per foot.
A lawful fence
Chapter 359A.18 of the Iowa Code states: A lawful fence in Iowa shall consist of:
- Three rails of good substantial material fastened in or to good substantial posts not more than ten feet apart.
- Three boards not less than six inches wide and three-quarters of an inch thick, fastened in or to good substantial posts not more than eight feet apart.
- Three wires, barbed with not less than thirty-six iron barbs of two points each, or twenty-six iron barbs of four points each, on each rod of wire, or of four wires, two thus barbed and two smooth, the wires to be firmly fastened to posts not more than two rods apart, with not less than two stays between posts, or with posts more than one rod apart without such stays, the top wire to be not more than fifty-four nor less than forty-eight inches in height.
- Wire either wholly or in part, substantially built and kept in good repair, the lowest or bottom rail, wire, or board not more than twenty nor less than sixteen inches from the ground, the top rail, wire or board to be between forty-eight and fifty-four inches in height and the middle rail, wire, or board not less than twelve nor more than eighteen inches above the bottom rail, wire or board.
- A fence consisting of four parallel, coated steel, smooth high-tensile wire which meets requirements adopted by ASTM International (formerly, American Society of Testing and Materials) including but not limited to requirements relating to the grade, tensile strength, elongation, dimensions and tolerances of the wire. The wire must be firmly fastened to plastic, metal or wooden posts securely planted in the earth. The posts shall not be more than two rods apart. The top wire shall be at least forty inches in height.
- Any other kind of fence which the fence viewers consider to be equivalent to a lawful fence or which meets the standards established by the department of agriculture and land stewardship by rule as equivalent to a lawful fence.
Gerrish, J., Fence Systems for Grazing Management, University of Missouri, Forage Research Center, Linneus, MO
Morrical, D., Wells, G., & Shouse, S., Fencing Systems for CRP Land, Iowa State University Extension, Ames, IA, 1994 (CRP-8)
Turner, L.W.; Absher, C.W.; & Evans, J.K. Planning Fencing Systems for Intensive Grazing Management, University of Kentucky Cooperative Extension Service
Wilson, R.K. and Clark, R.T. Costs of Cattle Fencing for Grazing Areas, University of Nebraska Cooperative Extension, 2002, (EC 830)