Guide for Chain Link Security Fencing Design and Construction

  1. Before install the chain link security fence, you should confirm the following points.
    • Prior to installation of a chain link fence, all necessary clearing and grading should be performed on both sides of the fence line. Grading along the fence line should minimize uneven surfaces that can lead to washouts and gaps under the fence. At gate locations, grade surface as level as practical consistent with drainage requirements between the hinged and latch posts and within the swing area of the gate. Grading for slide gates should comply with manufacturer's guidelines for smooth free of binding operation.
    • Where underground utility lines cross fence lines, consider how the framework and fastening can accommodate removal for maintenance should need arise without comprising the perimeter.
  2. The top of the concrete post footings shall be tapered to drain water away from the post and set 6 in. (152 mm) below grade to avoid heaving due to frost. Fence designs requiring larger posts or closer post spacings due to wind load or increased security may require larger, deeper concrete footings depending on soil conditions.
  3. Chain link fabric shall be placed on the outside of the secured area.
    • Pre-coated chain link fabric is available in widths up to 20 ft (6.09 m). Consideration should be given to require the chain link fabric to be of one width.
    • The chain link fabric shall be sufficiently stretched taut so as not to deflect more than 3 in. (76 mm) in the center of the fence panel in between the two line posts when subjected to a 30 lb (133 N) horizontal force.
    • Fences constructed using chain link fabric greater than 12 ft (3.66 m) in height may require an intermediate rail based on chain link mesh and level of security. The intermediate rail, when specified, shall be installed no less than 8 ft (2.43 m) above grade.
  4. Intermediate rail is required when two different chain link fabrics are installed such as 3/8 in. (10 mm) mesh at the top and 1 in. (25 mm) or 2 in. (50 mm) mesh at the bottom. The two fabrics shall be overlapped 6 in. (152 mm) and tied to the intermediate rail no greater than 12 in. (305 mm) on center.
  5. Based on the height of the fence, deleting the installation of top rail may be considered to eliminate a handhold for an intruder. For added security for fences using a top rail, install the rail 12 in. (305 mm) below the top of the mesh.
  6. Tie wires for the line posts, top, mid or bottom rail and terminal post brace rail shall be installed no greater than 12 in. (305 mm) on center.
    Post and rail ties shall be installed around the post or rail and the tie wire ends twisted around the chain link mesh a full three twists or wrapped a full 360 degrees around the post having the two ends of the tie wire twisted three full twists.
  7. Tension wire shall be installed at the top or bottom of the fence in the absence of top or bottom rail. The tension wire shall be secured to the chain link fabric with hog rings spaced no greater than 12 in. (305 mm) on center.
    Top tension wire, when installed shall be placed no less than 6 in. (152 mm) from the top of the mesh, bottom tension wire shall be installed no greater than 6 in. (153 mm) from the bottom of the mesh.
  8. Barbed arms when specified shall be riveted or bolted to the post.
  9. Bottom rail, when specified, shall be connected to the line post using boulevard clamps. The rail shall be secured to the boulevard clamp by drilling through the clamp, rail, and through bolting. The boulevard clamp shall be riveted or bolted to the post. Bottom rail shall be connected to the terminal post using a brace band and rail end. The rail end and bottom rail shall be through bolted and the brace band bolted or riveted to the post.
    • Additional security at the bottom of the fence can be obtained by securing and anchoring the bottom rail in the center of the two line posts using a 1/2 in. (25 mm) diameter galvanized steel hook set in a concrete footing.
    • Additional security can be obtained by burying a separate section of polymer coated chain link fabric of the same gauge and mesh as the adjacent fabric a minimum of 24 in. (610 mm) below grade. Overlap the buried fabric with the fence fabric a minimum of 6 in. (153 mm). It is recommended not to hog ring the two fabrics together leaving the buried fabric free to adjust to possible movement due to frost.
  10. Barbed tape shall be installed.
  11. All bolts, when applicable, shall be carriage bolts. All nuts and bolts, including those used on gates, hinges, latches, barbed arms, fittings, shall be installed having the nuts located on inside secured area and peened over to prevent removal.
  12. Installation of anti-ram systems:
    • Passive anti-ram systems, when required, shall be integrated with, attached to, or installed immediately behind the fence system.
    • Anti-vehicle crash gates when specified shall be installed as required to meet specified crash test rating.
  13. Grounding of fence when required shall be installed by a licensed electrical contractor.