Installing Wire and Line
Installing Wire or Line: Securing the Fence Top
The top of the deer fence should be left visually undefined. As noted earlier, the deer have trouble seeing our polypropylene or metal fencing. They especially have trouble telling how tall these fences are, and so they don’t know how high they need to jump. If you put something on the top of the deer fencing that defines it (like, say, a two-by-four board), then that will lead the deer to think (correctly) that the fence ends there and will present them with an invitation to jump. Since you don’t want to send this invitation, you should avoid putting anything along the fence top that defines the fence’s upper boundary. However, you do want to provide support along the top of the fence–something that can be done with nylon monofilament line or pvc-coated steel tie wire.
Thick nylon monofilament lines (8 or 12 gauge) and pvc-coated black 13.5 gauge steel tie wire are used to improve the deer fence’s appearance and to strengthen it against falling tree limbs, charging deer, or deer that persistently butt against the fence (see video).
Tie wire requires less gear to install than nylon monofilament (no special terminators or tighteners are needed). Also, since the wire need not be placed under much tension, it minimizes the need for earth anchors and also puts less of a pull upon posts along a curve, and so limits the tendency of such posts to tilt toward the curve’s inner side (see diagram below)
On the other hand, monofilament line tends to give with the fencing (which has some give to it); whereas tie wire, which does not give at all, breaks first. So when placed along the top of the fence nylon monofilament is better at warding off falling branches; and when placed in the “deer impact zone” at a height of 3 to 4 feet it is better at countering the effects of deer inclined to charge the fence or give it a persistent battering.
We recommend using tie wire (1) at the tops of garden deer fences where the distance between any given pair of corners, gates, and ends is short; and (2) wherever the fence goes around a curve (apply a series of tie wire lengths to negotiate the curve).
Note that whatever type of line or wire is used, this line or wire should be applied in a series of “runs” starting at one end, gate, or corner on the fence and ending at some intermediate point or at the next corner, gate, or end. If using tie wire keep the runs relatively short (not over 80 feet and considerably shorter than that if going around a curve). Even if you are using monofilament line the runs should not span more than 300 feet, so if you get to the 300-foot mark terminate the run at the nearest post and start another.
If a polypropylene deer fence blocks places where deer have been accustomed to roam freely, it is advisable to install two monofilament lines about 9 inches apart in the “deer impact zone” 3 to 4 feet high in order to minimize damage to the fence. This step is not necessary in the case of metal deer fencing unless it becomes clear after installation that the fence is being subjected to severe battering.
Installing Monofilament Line
For those not installing wire, we offer nylon monofilament line in two diameters, 8 gauge and 12 gauge. These lines resist UV radiation well and are reasonably durable, having an expected life of 5 to 10 years. They can be connected to the deer fence with hog-ring staples, zip-lock ties, or short lengths of tie wire; and they can be drawn tight and secured to posts or trees with gripples and a gripple tensioning tool, or with u-bolts and circular wire tensioners. Alternatively, if you are using wood posts or trees, the line can be tightened and secured without special gear as follows: Hammer a two-inch U-nail about half-way in on the outside surface of the tree or wood post to which the line is being secured. Then cut the line, string it through the U-nail opening twice, pull the filament taut, and hammer the U-nail down far enough to hold the filament securely but not far enough to harm or break it. Who said there was no art to installing a deer fence?
The main weakness of this monofilament line is that it stretches. So every year or two one needs to inspect it to see whether it is sagging. If it is, use a gripple tensioning tool (for a line secured by gripples) or a circular wire tensioner tool (for a line bearing a circular wire tensioner) to tighten the line of monofilament. Or, if one is using wood posts or trees, go from the U-nail where it is attached to the tree or wood post and move the line horizontally back over the tree or post until the line has regained the desired tightness, and at this point drive a U-nail over the re-positioned strand to keep it taut.
Figuring Runs of Line
Runs of monofilament line should not exceed 300 feet, and runs of metal tie wire should not exceed about 80 feet. So assuming your deer fence has only one monofilament line or tie wire (at the top), calculate the number of runs by starting at a corner and going up to 80 or 300 feet or until you reach the first corner, gate, or end. Stop the run at that point and start a new one. Whichever device you choose (gripple or u-bolt cable clamp) if you are using a monofilament line you will need two of these devices for each run (none of these are needed with tie wire). If your choice is u-bolts, you will also need one circular wire tensioner per run.
Installing Wire (Metal Tie Wire)
Compared to installing nylon line, installing wire is easy. 13.5 gauge pvc-coated steel tie wire does not stretch, and it does not need to be applied under tension. Simply pass one end of the tie wire around one anchor post, wrap it around itself a few times to form something that looks like a small hangman’s knot, proceed to the other anchor post (at the other end of the run), pull the wire tight enough to run straight and support the fence, cut the wire, and wrap the cut end around the incoming wire several times to form another small hangman’s knot.
As noted above, use this wire in preference to nylon monofilament (a) wherever the deer fence goes around a curve and (b) at places where a “run” of deer fencing is going to be less than 60 feet long.
Support Lines for Metal Hexagrid Deer Fencing
Unlike polypropylene fencing, which may need to be strengthened by lines running through its mid-section (see above), metal hexagrid fencing already has horizontal reinforcing wires running through it at regular intervals, and both it and welded wire fencing are generally strong enough to resist multiple deer impacts. Therefore, unless one is interdicting a large and well-established deer path, the only monofilament line or tie wire needed is the single one along the top that helps to support the fence’s weight.