Why Fences in Tempe Wear Out Where They Do
A fence in the Valley leads a different life from a fence in a wet climate. It does not sit damp for months and it does not quietly rot away. It bakes. Then for a few weeks each summer it gets hit by wind that arrives all at once and is gone in twenty minutes.
So the wear turns up in two places. At the top, where years of sun have worked on the boards and the finish, and at the bottom, in a narrow band where the post meets the ground. The middle of a fence is rarely the problem.
The sun does the work that rain does elsewhere
Wood does not need moisture to age here. Sun grays it, dries it and opens splits along the grain, and as the boards shrink, the nails and screws lose their grip. That is why a fence starts rattling in the wind a year or two before anything visibly breaks.
Vinyl depends on what grade it was to begin with. Panels made for this sun keep their color and hold their line. Cheaper panels go brittle, and once they are brittle a gust or a stray ball is enough to crack one.
Iron has the easiest life of the four until its coating wears thin, and then it starts marking at the bottom of the pickets, which is where the irrigation reaches it. The runs that go first are the ones facing west and south, taking the afternoon of every summer. A fence on the shaded side of the same house can look years younger.
Everything comes down to the ground line
Look at a failing wood fence and the wood a foot off the ground is often still sound. The damage sits in a band right where the post enters the ground. Steel and chain link posts do the same, showing a rust line at almost exactly that height.
The usual reason one post goes while the two on either side hold is water that keeps arriving. A sprinkler head throwing onto the base of a post, or a drip line that has worked its way over. Move the water and the replacement post lasts a good deal longer.
Wind then finds whatever is already loose. A fence that goes over in a monsoon storm has almost always had a weak post for a while. The storm gets the blame, and all it really did was pick the spot.