2008 May Lumber Talk.com: Professional-Level information and how-to-build articles for wood, timber, and lumber professionals and users. 2008 May » Lumber Talk

The life span of your treated posts posts matters. Before spending thousands, or tens of thousands, of dollars on a fence it is nice to have a better idea of how long you can expect your investment to last.

So, to answer the question: How long will my treated posts last?

According to the Southern Pine Council you can expect properly treated posts to last many decades. They site a study by USDA Forest Service’s Forest Products Laboratory saying:

Test stakes of treated wood have been buried in the ground at various locations, stretching from the Mississippi Delta to the Canadian border. Data analysis indicates that CCA-treated Southern Pine stakes in place since 1938 have shown no failures at chemical retention levels of 0.29 pounds of preservative per cubic foot of wood, or higher.

Most treated posts are treated to a retention of .40 but you should always ask – just to be safe.

Here’s a great pdf from the USDA with expected life spans for various species of treated posts including a comparison of the life spans of treated and untreated posts (see page two).

If you want a guarantee that your posts will last you can get treated posts coated at the ground line from American Pole and Timber. I mentioned these posts before in How to Build a Fence that Lasts because I have seen them up close and they are tough. They claim that posts coated at the ground line with their poly coating will last fifty years.? In reality, the posts should last 150 years because the ground line is the source of infestations and the place where decay begins.? If that is protected, you don’t have much else to worry about.

The bottom line is that the life span of properly treated posts should be at least 20 years and can be easily extended to 50+ when installed and used in normal conditions (not in water or along the coast, for instance) .? If you choose the right materials, your grandchildren won’t even have to deal with building another fence.