Fences are either open, to use as a trellis for roses or other plants, or they are closed to serve as a wind, sun or privacy screen. The materials will depend largely upon the use to which the fence is to be put. The most popular, and probably the most attractive, fences are built of wood in various forms, but newer fences of asbestos-cement and corrugated sheet metal are colorful and stand up against rot better. Because they are heavier, they are usually erected in a zigzag design, the better to stand up against prevailing winds.

The major problem in prolonging the life of a fence stems from rot at the ground line, for here it is susceptible to alternating wet and dry conditions. Among the best woods for withstanding rot are California redwood and Southern cypress, white cedar and red cedar,chestnut, locust and arbor vitae. While painting the wood with preservatives often lengthens the life of your fence, this will do no good unless the preservatives penetrate. That's why a post that has been machine-creosoted will resist rot, while a hand-creosoted post will not. However, if you use a good preservative on a clean, dry, unpainted wood, and give the wood two or three coats, you can do a good job.

Among the commercial wood preservatives you will find those of pentachlorophenol, copper napthe-nate (which has a green color) and zinc napthenate, a clear solution.In addition to the point where the post hits the ground, any place where two pieces are nailed together on a wooden fence is subject to rot. Therefore, it is wise to treat the wood where the members are joined before you put up the fence. This will preserve it much better than painting afterward.