When building a wood privacy fence there are two types of posts that are typically used: wood and steel. The choice of posts will in large part determine how long the fence will last. Be sure to compare the quality, price and longevity of the posts. Keep in mind that the cost of the posts is actually only a small portion of the total cost of the fence. Wood posts are usually thought to be the most cost efficient but that may not always be the case.
A wood post is often the most popular choice for a cedar privacy fence. The posts are usually cedar or pressure treated pine. Most commonly they are 4 "x 4" or 6 "x 6" inches in size.
Cedar is a naturally rot-resistant species of wood. A cedar post can make for a beautiful wooden fence. But even cedar posts will decay when in contact with warm moist earth. And cedar posts are not inexpensive either.
Treated posts are usually made out of pine, hemlock or fir and are then soaked with chemicals to resist decay. This type of post is usually the most economic choice initially. The chemicals used are often copper based because copper has anti-microbial properties. Many of them are complex compounds that go by acronyms such as CCA, ACQ, CA or Copper-Nap. Some of these chemical treatments contain elements which are known to be toxic to living things. There is some concern that these chemicals can leach into the soil and water.
For maximum wind resistance it is recommended by most fence professionals that the diameter of the hole be 3 times the diameter of the post itself. This means that a wooden 4 x 4 post requires a 12 "diameter hole.
A steel post usually costs more than a wood post. But that extra cost may be offset by the fact that it will never rot or decay. And because a steel post requires a smaller diameter hole it will use less concrete. A steel post does not need any gravel for drainage and they use 6 "diameter holes that are easier to dig.
Steel posts are typically galvanized to resist corrosion and will last a lifetime. They come in three basic shapes: round posts that require brackets and a cap, hat-channels and C-posts. Unlike a wood post a steel post will never twist or warp.
The only major drawback to using steel instead of wood is the fact that steel posts do not look very nice with a wood fence. There are however metal posts available that can be covered to look like wood. By using this type of post you can get the attractive look of wood with all the benefits of steel.
When choosing the posts for a wood privacy fence be sure to compare their quality, price and longevity. Wood posts may seem to be the better buy at first glance. But when the price of concrete and gravel are included, a steel post can actually cost less than a wood post. And a steel post will make the fence last longer giving it added value over time.