Fence glossary · Structure
Tension wire
A heavy-gauge, usually coiled-spring steel wire run along the bottom — and sometimes the top — of a chain link fence and tied to the fabric, holding the mesh against the ground line. It is what stops the bottom of a chain link fence being pushed up or pulled away from the posts.
Without it, chain link fabric is only held at the terminal posts and along the top. The bottom is free, and it behaves like it: the mesh billows between posts, an animal noses under it, and a mower catches the loose edge and pulls it. Tension wire is stretched between terminals, tightened, and hog-ringed to the bottom of the fabric at intervals so the whole bottom edge acts as one line.
The alternative is a bottom rail, and the choice comes down to ground. A rail is rigid and holds a dead-straight line, which suits flat sites and reads as the more finished detail. Tension wire follows grade, which is what the rolling clay ground across Chester County and the Route 1 corridor actually gives you — a bottom rail on a gently undulating line either leaves a gap under it or has to be stepped at every post. On a run that rises and falls continuously, tension wire is the better answer and the faster one.
Top tension wire does a different job. On a standard residential fence the top gets a rail, which stiffens the whole assembly and gives it a finished edge. On tall fabric, and on commercial and basin enclosures, a top tension wire is used instead: it lets the fabric flex under load rather than transmitting the hit into the framework, and it removes the horizontal rail that would otherwise be the obvious foothold.
