Will Fence Posts Rot In Concrete?

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This has been a hotly debated topic for quite some time with many theories being offered in favor of or against setting posts in concrete. There are many different methods of sinking posts into the ground and depending on where you go in the country, you might see one method largely preferred over another. Along with methods come add-ons like concrete collars and methods like sloping the concrete up towards the post, this usually occurs in colder climates, but to answer the question at hand, let’s first discuss what “rot” actually is and what causes it.

The thing that causes wood posts to deteriorate and weaken is actually a living organism. Rot is a very hungry organism that feeds itself with wood posts. It typically lives up to about 5 inches above ground level and down to about 8 inches beneath the ground. You won’t often see a post rotted further down than 8 inches below. The reason for this is because oxygen is necessary for rot to exist and the further beneath the ground you go, oxygen becomes scarce. Any living organism needs 4 things to thrive and grow: food, water, oxygen, and the proper temperature.

Does Concrete Cause Posts to Rot?

While some think that sinking in posts with concrete causes moisture to get locked in to the post, it’s more common to see the rot exist above and below the concrete. Though the rot doesn’t usually occur within the section covered by concrete, it’s very apparent that concrete doesn’t do anything to prevent rot either. The wood post essentially acts as a straw and can suck up moisture from the bottom of the post hole. In the case of treated wood, over time the wood can expand and twist and cause a gap between the wood and concrete, letting in moisture.

Butler Contracting Recommendation

Our preference at Butler Contracting is not to use concrete, but to simply drive the metal post deep into the dirt when possible. When dirt is dry, it actually does a pretty good job at soaking up moisture. It also can conduct heat through the sun, causing temperature irregularity making it more difficult for rot to sustain. When installing wooden fence posts, we recommend anchoring them in concrete.  Not so much to prevent rot, but they are more stable in our area based on the soil conditions. In some areas the soils are conducive to not using concrete, but it still won’t make your posts completely impervious to rot. On average, wooden posts last 8-10 years while metal posts can last 25-30 years.  At Butler Contracting we strictly use Postmaster fence posts whenever possible, and those posts come with a 15 year manufacturer warranty.

Have Butler Build Your Fence!

Though fencing has many factors that can affect price, we have a great Fence Estimator Tool to simplify the process. Click the link and start filling out the info or if you’d prefer to talk to us directly, give us a call at (844) 628-8537.