NATURAL RESOURCES CONSERVATION SERVICE



NATURAL RESOURCES CONSERVATION SERVICE

CONSERVATION PRACTICE STANDARD

FENCE

(Ft.)

CODE 382

DEFINITION

A constructed barrier to animals or people.

PURPOSE

This practice facilitates the accomplishment of conservation objectives by providing a means to control movement of animals and people, including vehicles.

CONDITIONS WHERE PRACTICE APPLIES

This practice may be applied on any area where management of animal or human movement is needed.

CRITERIA

General Criteria Applicable to All Purposes

Fencing materials, type and design of fence installed shall be of a high quality and durability. The type and design of fence installed will meet the management objectives and site challenges. Based on need, fences may be permanent, portable, or temporary.

Fences shall be positioned to facilitate management requirements. Ingress/egress features such as gates and cattle guards shall be planned. The fence design and installation should have the life expectancy appropriate for management objectives and shall follow all federal, state and local laws and regulations.

Height, size, spacing and type of materials used will provide the desired control, life expectancy, and management of animals and people of concern.

Table 1 shows criteria for selecting fence types based on intended use, number of wires and height. Appendix 1 includes material and installation specifications for materials and installation.

CONSIDERATIONS

The fence design and location should consider: topography, soil properties, livestock management and safety, livestock trailing, wildlife class and movement, location and adequacy of water facilities, development of potential grazing systems, human access and safety, landscape aesthetics, erosion problems, moisture conditions, flooding potential, stream crossings, and durability of materials. When appropriate, natural barriers should be utilized instead of fencing.

Locate fences (division fences) to help facilitate management of different landuses and special management areas within landuses such as ecological sites, pasture types, riparian areas, critical eroding areas, etc.

For domestic livestock, install fences in areas that will best facilitate the handling, feeding, watering and movement of the type of livestock managed. Consider fencing along the contour to minimize livestock trailing and subsequent erosion.

When installing interior fences to facilitate livestock movement (cross fencing), temporary fences should be considered in order to minimize costs and allow for flexibility in the system. Locations should allow for the shortest and straightest distances.

For horses, consider avoiding the use of barbed wire when possible in order to minimize potential injury, especially when areas of confinement are small.

When installing fences in areas of heavy wildlife movement / traffic (such as riparian areas) consideration should be given to wire types and spacing. Spacing of top and bottom wires should be adequate for the movement of the types of wildlife managed for. Where barbed wire is used, the cooperator should consider smooth wire for the top and bottom wires to reduce potential for harm to deer jumping over fence.

When planning and installing fences in areas of known prairie chicken habitat, consider using approved marking methods to help prevent bird collisions and minimize mortality. Guidance for fence marking can be found at .

Where applicable, cleared rights-of-way may be established which would facilitate fence construction and maintenance. Avoid clearing of vegetation during the nesting season for migratory birds.

Fences across gullies, canyons or streams may require special bracing, designs or approaches.

Fence design and location should consider ease of access for construction, repair and maintenance. Where practical, in order to minimize maintenance and installation costs, avoid areas such as rough and irregular terrain, excess trees and brush, areas with long-standing water and water crossings

Fence construction requiring the removal of existing unusable fence should provide for the proper disposal of scrap materials to prevent harm to animals, people and equipment.

FENCE TYPES

The overall effectiveness of each type of fence and the costs for installation and maintenance, depends on type of animal controlled, the number and size of wires used, posts type and spacing.

Standard Post and Wire Fences are the most common fence type used for controlling all types of livestock. They are suitable as permanent fences in areas that receive moderate to heavy pressure from livestock. They are typically barbed wire or double strand smooth wire.

Permanent Energized (Electric) Fences provide a low cost alternative and more flexibility to the other types of fences. They are mostly used for interior cross fencing but can also be used for boundary fences. They can be powered by a variety of types of energizers. Livestock must be trained to respect electric fences if they are to be effective.

Suspension Fences are a low cost variation of the standard post and wire fence and can be used as either boundary or interior cross fencing. They are typically used on large pastures with level terrain. They can be either barbed wire or smooth wire. The fence design allows it to sway (move) in the wind and when contacted by animals.

Woven, Net and Mesh Wire Fences are best suited in areas where tight control is necessary such as with sheep, goats, horses, hogs, people or predator control. These fences consist of multiple rows of horizontal smooth wires held apart by vertical wires, usually of different sizes and configurations. Space between wires varies depending on designated use.

Temporary Electric Fences are only used for interior cross fencing, areas needing temporary protection / exclusion (i.e. during vegetation establishement) and areas where pressure from livestock is not heavy. They can be easily attached to permanent fences and can be of either high tensile smooth wire, net fencing (for use with sheep and goats), polyethylene twine and/or tape.

High Tensile, non-energized fences are suitable as permanent fence in areas that receive moderate to heavy pressure from livestock but require more strands of wire than barbed wire to maintain the same level of control. These fences are safer for domestic animals, especially horses, and wildlife than are the barbed wire fences

Other Fence Types include chain link, pipe, vinyl, galvanized panel, board and cable fences. These fences are generally more expensive to install and maintain. They are generally used around corrals and homesteads. They may be used to restrict access to unsafe areas such as lagoons, abandoned mines and other unsafe or sensitive areas. When used for livestock control, they will be designed based on type of animal controlled.

PLANS AND SPECIFICATIONS

Plans and specifications are to be prepared for all fence types, installations and specific sites. Requirements for applying the practice to achieve all of its intended purposes shall be described.

OPERATION AND MAINTENANCE

Regular inspection of fences should be part of an ongoing maintenance program. Inspection of fences after storms and other disturbance events is necessary to insure the continued proper function of the fence. Maintenance and repairs will be performed in a timely manner as needed, including tree/limb removal and water gap replacement.

Remove and properly discard all broken fencing material and hardware. All necessary precautions should be taken to ensure the safety of construction and maintenance crews.

References

Bell, H.M. 1973. Rangeland management for livestock production. University of Oklahoma Press.

Heady, H.F. and R.D. Child. 1994. Rangeland ecology and management. Western Press.

Holechek, J.L., R.D. Pieper, and C.H. Herbel. 2001. Range management: principles and practices. Prentice Hall.

Stoddard, L.A., A.D. Smith, and T.W. Box. 1975. Range management. McGraw-Hill Book Company.

United States Department of Interior, Bureau of Land Management and United States Department of Agriculture, Forest Service. 1988. Fences. Missoula Technology and Development Center.

United States Department of Agriculture, Natural Resources Conservation Service. 2005. Electric fencing for serious graziers. Columbia, Mo.

United States Department of Agriculture, Natural Resources Conservation Service. 2003. National range and pasture handbook, revision 1. Washington, DC.

Vallentine, J.F. 1971. Range development and improvement. Brigham Young University Press.

Planning Fences, American Association for Vocational Instructional Materials, Third printing, 1997

Building Fences, American Association for Vocational Instructional Materials, 1974

Fence Brace Assemblies, Circular 792, Institute of Food and Agricultural Sciences, Rev. 1992

ASTM STANDARDS 116,121

Fences, USDA Forestry Service Handbook, Feb. 1999

|Intended Use |Fence Type |Minimum Number |Average Height |Max Line Post |MAX LINE POST |

| | |of Wires |Top Wire1 |Spacing |SPACING W/ 2 OR |

| | | | |W/O STAYS1 |MORE STAYS |

| | |4 |44-48 | | |

| | |5 |48-52 | | |

| |SUSPENSION |4 |44-48 |N/A |1003 |

| |SMOOTH, HIGH TENSILE, NON-ENERGIZED; |5 |48-52 |20 |30 |

| |Double strand, non-barbed | | | | |

| |Smooth, high tensile, Energized |3 |38-42 |75 |150 |

| | |4 |44-48 | | |

| |Woven Wire (Addition of 1-2 barbed |NA |42-48 |N/A |N/A |

| |wires may be added to achieve total | | | | |

| |height) | | | | |

|Goats / Sheep |Woven Wire (Caution with horned goats) |NA |32-42 |N/A |N/A |

| |Standard Barbed Wire |7 |38-42 |15 |20 |

| |Smooth, high tensile, non-energized; |7 |38-42 |15 |20 |

| |Double strand, non-barbed | | | | |

| |Smooth, high tensile, Energized |5 |34-38 |75 |150 |

|Horses |Board |NA |48 |N/A |N/A |

| |Woven, Mesh |NA |42-48 |N/A |N/A |

| |Standard Barbed Wire |4 |48-52 |20 |30 |

| |Smooth, high tensile, Energized |4 |48-52 |75 |150 |

| |Smooth, high tensile, non-energized ; |5 |52-56 |20 |30 |

| |Double strand, non-barbed | | | | |

|Large Wildlife |Woven |NA |96 |N/A |N/A |

|All |Temporary (portable), Energized2 |1-3 |2/3 shoulder |N/A |N/A |

|Livestock | | |height of animal | | |

Table 1: Minimum criteria for selection and installation of fences. Fence design and construction must meet or exceed these criteria.

1. Exception is for all property boundary fences, which shall be a minimum of 54 inches for all fence types. Spacing may need to be narrower depending on terrain and pressure from livestock. Lanes, holding pens, areas around watering and feeding facilities as well as property boundaries will have a maximum spacing of 16 ½ feet.

2. Temporary / Portable fences are only used for interior crossfencing or for temporary protection of areas (i.e. critical area during vegetation establishment). Should not be used for areas that will receive heavy livestock pressure. May be smooth high tensile steel, aluminum, galvanized, polywire or polytape (See Table 2 for wire requirements)

3. Stays will be installed at no more than 15 foot intervals between posts. They should swing free of the ground to permit the fence to sway. Stays will be constructed of durable materials designed for this purpose.

APPENDIX 1: MATERIALS and CONSTRUCTION SPECIFICATIONS

Variations from materials and construction may be approved if sufficient documentation is provided to the State Resource Conservationist that proves the variations will result in an installation that will meet or exceed this standard and specification

I. WIRE

All wire will be of new galvanized material and in accordance with criteria outlined in Table 2 which follows American Society of Testing Materials (ASTM) standards.

Table 2 Minimum Criteria and Specifications for Wire

|Wire Type |Minimum Wire Size |1/ Other Requirements (Protective coatings, Tensile Strength / |

| | |Breaking Load) etc. |

|Standard Double Strand Barbed wire|12 1/2 gauge |Class I galvanized. Meets ASTM-121 |

| |(Barbed will have 14 gauge or heavier |70,000 psi / 950 lbs. breaking load |

|Standard Smooth double strand wire|two-point barbs spaced 4-6 inches apart.) | |

|Standard Smooth single strand |9 gauge |Class I galvanized. Meets ASTM-121 |

| | |70,000 psi / 950 lbs. breaking load |

|High-Tensile Double Strand Barbed |13 ½ - 15 ½ gauge |Class III galvanized. Meets ASTM-A854. Heat treated High Tensile. |

|Wire | |170,000 psi |

|High Tensile Smooth single strand |12-1/2 gauge | |

|Standard Woven Wire |Top & Bottom wires: min. 11 gauge |Class I zinc coating or equivalent. Meets ASTM 116. 32 -48 inches |

| |Intermediate & Stay Wires: min. 14-1/2 gauge |minimum height; Maximum 12 inch spacing between stay wires. |

|High Tensile Woven Wire |14 1/2 gauge |Class III zinc coating or equivalent. Meets ASTM 116. 32 inches |

| | |minimum height ; Maximum 12 inch spacing between stay wires. |

|Mesh Wire; such as Horse-No-Climb |Top & Bottom wires: 10 gauge |Class I zinc coating or equivalent. At least 48 inch high, less than|

| |Intermediate & Stay Wires: 12-1/2 gauge |or equal to 2 inch x 4-inch mesh spacing. |

|Polywire or “ Twine-Type “ |Minimum of 8 strands of aluminum or stainless|Wires interwoven with polyethylene or polypropylene fiber. Only |

| |steel filaments |used for temporary fences and where pressure from livestock is not |

| | |heavy. |

| | |The polywire (twine-type) is more durable especially when it is |

| | |being rolled up and moved often and should be used when multiple |

| | |wires are planned. |

| | |Polytape (tape-type) is best used in situations where high |

| | |visibility is a concern such as with horses. |

|Polytape or “Tape-Type” |Minimum ½ inch wide and 5 strands of aluminum| |

| |or stainless steel filaments | |

|Galvanized Steel |14 gage |Use for 1 to 2 wire temporary fences. |

| | |150,000 psi / 690 lbs. breaking load |

|Aluminum | |Use for 1 to 2 wire temporary fences. |

| | |38,000 psi / 215 lbs. breaking load |

1/ Wires designated as regular, commercial and utility grade wires are available but do not offer the level of treatment as the Class I and III. Cooperators should be informed of this fact when considering wire. These types are not included in this standard. Most wire manufacturers include wire specifications on fence tags. If information is not provided or known, lab testing may be needed to determine strength of wire.

WIRE SPACING

Height of the top wire will be as specified in Table 1. Fences for large animals like cattle will have the bottom wire a minimum of 12 inches from ground and no more than 16 inches. The top wire will be based on intended use (Table 1.). All other wires should be equally spaced. For smaller animals like sheep and/or goats, the bottom wire shall be no more than 5-6 inches up from the ground and maximum spacing between lower wires (lower 18-20 inches of fence) will be 8 inches. When there is a combination of livestock, such as cattle and sheep, the lower wires shall be designed for the smaller animal and overall height will be for the larger animal.

INSTALLATION OF WIRE

Fence wire will be stretched to sufficient tension prior to being fastened to posts. Temperature variations must be considered (wire will tighten in cold weather and expand in hot weather).

For suspension fences, wire tension is critical and wires should be stretched to allow no more than 3 inches of sag between posts set at 100 feet and 1.5 inches for posts at 50 feet.

Wherever possible, wire will be attached to fence post on side receiving most pressure, at top wire heights based on intended use (Table 1.)

ATTACHING WIRE TO POSTS

The following criteria will be followed for attaching wires to line posts:

Staples

• 9 gage steel with a minimum length of 1 ½ inches for soft woods and 1 inches for hardwoods.

• Drive staples diagonally to the wood grain at a slight downward angle (upward if pull is up) to avoid splitting the post.

• Space will be left between post and staple to allow free movement of wire and to avoid damage to zinc coating.

Manufactured wire clips or 12-12 ½ gauge galvanized wire can be used. Wire clips or drilled holes can be used for fiberglass posts

Insulators (electric fences only)

• Porcelain, ceramic, high quality UV Stabilized polyethylene or equivalent insulators will be used on wood and steel line posts as well as corner and end assemblies.

• Offset Brackets can be attached to standard fences at intervals of 50-60 feet and a height equal to 2/3 the height of the animal controlled.

WIRE SPLICES

Standard Wire - Western Union splices are the preferred method and shall have a minimum of 8 wraps on each side of center tightly wound and closely spaced. An accepted alternative method is the “double loop knot” splice where the wire has a minimum of 8 wraps on each side of the loops. Do not use the “double loop knot” on high tensile wire.

High Tensile Wire – “Figure – 8” splice will be used by overlapping wires 2 inches, looping each wire over and back through, then pulling together. As fence is stretched the splice will tighten.

Standard and High Tensile Wire - Compression fittings or splice sleeves will have a tensile strength not less than 80% of the wire. Ends of wire will be overlapped at least 2 inches with two sleeves fitted over wires and firmly crimped.

IN-LINE STRAINERS

In-line strainers will be used to maintain tension in permanent, high tensile steel, smooth wire fences. They will be placed near center of fence line to achieve equal tension at both ends of the line. They should be installed on each wire between each pull assembly and a distance not to exceed 4,000 feet for straight line stretches and 1200 feet for uneven terrain or non-straight stretches.

II. POSTS

The criteria for posts apply to all line posts and posts used for brace assemblies. Table 3 contains additional criteria for line posts. Criteria for brace posts assemblies are found in Table 4 and Figures for braces.

Wood Posts - Must be new, sound and free from decay. Except for red cedar, mesquite, Osage orange, catalpa, and black locust, all wood posts shall be treated with a preservative which is approved by either Federal Specification TT-W-571 or the American Wood Preservers Association (AWPA).

Steel Pipe - Must be new and painted or galvanized for rust resistance. Posts will have the top closed to prevent rainfall from entering post.

Table 3 Minimum Criteria and Specifications for Line Posts

| |Minimum Diameter/ Weight |Minimum Setting Depths ( inches)1 |

|Line Post Type | | |

| | |Rocky Soils |Sandy Soils |All Other |

|Wood |3 inches |18 |30 |24 |

|Standard steel “T” or “U” - New, high carbon steel, galvanized,|1.25 pounds per foot of |Anchor plate must be fully into and below ground surface |

|enameled and baked, or painted with weather resistant steel paint.|length |(Approx. 15-18 inches) |

|Will have an anchor plate and be studded, embossed or punched for | | |

|wire attachment. | | |

|Steel Pipe |2 inches outside diameter |18 |30 |24 |

| |(OD) weighing 3.65 lb/ft or| | | |

| |equivalent | | | |

|The following criteria are applicable only for electric fences (most common use in temporary fences). Posts shall meet or exceed the requirements |

|provided by energizer manufacturer. Fiberglass posts will be a composite of marble fiberglass and polymer resin, treated by thermosetting |

|Fiberglass “T” |1 inch cross section |18 inches or depth recommended by manufacturer, whichever|

| | |is deeper. |

|Fiberglass Round |3/8 inch | |

|Manufactured ”Tread-in” Type posts |Rigid Plastic, PVC, other |For use with temporary electric fences only – Set at 18 |

| |synthetic posts |inches or depth recommended by manufacturer, whichever is|

| | |deeper. |

1. Minimum lengths of all posts will allow for required setting depths and fence height plus at least 2 inches of post above the top wire

Trees as line post. Fencing may be fastened to trees in rocky areas where postholes are impossible to dig or in frequently flooded areas where fences are difficult to maintain. Trees should be properly aligned and sturdy so that swaying and other movements will not affect the operation of the fence. A buffer (treated board) should be installed between the wire and the tree to keep the tree from growing around the wire. In places where a buffer cannot be attached to the tree, the staples driven directly into the tree must completely penetrate the sapwood below the bark.

LINE POST ALIGNMENT

Spacing for line posts will be the same for all types of posts used. Maximum spacing is provided in Table 1. Installation shall ensure that adequate fence height is maintained based on its purpose (see Table 1). Line posts will be set in as straight a line as possible between corners or turns. When fencing along curved lines, use straight sections with appropriate in-line bracing.

III. BRACING and BRACE ASSEMBLIES

Bracing of anchor (pull) posts is required at all corners, gates, and fence ends and at certain specified distances (determined by length of pull) at definite changes in slope and alignment changes in the fence line.

Brace assemblies are installed to anchor wire strands and are the foundation of a good fence. They are designed to resist the loads that are transferred from tensioned fence wires, contraction of wire due to weather, and shock loads from livestock pressure or fallen trees. Braces fail because of structural failure (improper design, poor materials, overstresses members), weak soil or soil movement (soils shear in front of posts, sandy soils) or post pullout (poor design or poor soils cant support tension). Therefore, criteria for brace assemblies account for soils, depth of post placement, number of wires (tension), terrain, materials and purpose.

End braces are required where fence ends and on both sides of gate openings. End braces will have an anchor (pull) post where wires are stretched and tied off and one or more brace posts installed in-line with direction of pull, in only one direction.

When a change of direction occurs, forces placed on posts that are not inline cause leaning, pulling out or complete failure. Therefore, bracing is required. For angles of change (see diagram) less than 20 degrees, a single steel or wood line post may be used for extra support.

Corner Braces are required at all points where the fence alignment has an angle of change of 20 degrees or more and the pull is from two directions. Corner braces are comprised of the anchor (pull) post where wires are stretched and tied off and one or more brace posts (depending on length of pull) installed in-line with direction of both pulls. Normal brace assemblies are best used when the angle of change is 60-90 degrees. Wires are tied off and stretched at the anchor post.

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Inside Braces – Best for when angle of change is 20-60 degrees. Wires do not have to be cut and tied off, but can wrap around outside post as long as it can be secured (held in place). Brace is installed as “H-Brace” or if using steel pipe, the brace can be an angle brace. Refer to materials and installation requirements for 2 post brace assemblies.

In – Line Pull Post assemblies are located in straight sections of the fence line with pulls in both directions where distance between anchor (pull) posts of corners or ends exceeds the distances outlined in Table 4. They allow for a point in which the wire can be tied off and stretched. They are also used where there are sudden changes in elevations, such as at the bottom and top of steep slopes, or on both sides of drainages / water gaps.

Brace assemblies contained in these specifications are those that have been proven for longevity, strength and quality. The primary types of braces used and selection criteria are found in Table 4 and Figures as shown in Table 4. Specifications for materials and installation are found in Table 5.

Table 4. Brace Selection and criteria based on type of fence planned

|Fence Types |Brace Assembly Types and Figure Reference |# Wires |Maximum Length of Pull (feet) |

|Standard wire fences (non-electric, |Single Brace – Ends and Corners (Figure |5 or more |660’ (firm, clay or loam soils) |

|electric and suspension) |1-3) | |330’ (sandy, rocky or prolonged |

| |These will be the most common brace | |wet soils) |

| |assemblies used for most situations | | |

| | |3 - 4 |1320’ (firm, clay or loam soils) |

| | | |660’ (sandy, rocky or prolonged |

| | | |wet soils) |

| |Double Brace – Ends and Corners (Figures |5 or more |1320’ ((firm, clay or loam soils) |

| |4,5) | |660’ (sandy, rocky or prolonged |

| |Used when fence loads or soil conditions | |wet soils) |

| |require increased brace strength | | |

| |In-Line Pull Assemblies (2-3 post wood, 3 |N/A |1320’ or length of roll of wire |

| |post steel, welded) | | |

| |(Figure 7) | | |

|Woven Wire |Single Brace – Ends, Corners (excluding |N/A |660’ |

| |slip brace) | | |

| |In-Line Brace Assemblies (2-3 post wood, 3|N/A |660’ or length of roll of wire |

| |post steel, welded) | | |

|Temporary Electric Fencing (Low tension |Anchor / Pull Posts (Figure 6) |2 or less |1320‘ (firm, clay or loam soils) |

|applications) | | |660’ (sandy, rocky or prolonged |

| | | |wet soils) |

|Temporary Electric Fencing (High tension |Anchor / Pull Posts with Brace |2-3 |1320‘ (firm, clay or loam soils) |

|applications) |(Figure 6) | |660’ (sandy, rocky or prolonged |

| | | |wet soils) |

|Where rocky or shallow soil conditions do not allow for setting posts, rock baskets may be used for | ................
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