Over the years I’ve replaced many wood fence posts as part of a repair on replacement project. Depending on the age of the fence the posts can be in various states of condition. Some are still solid with very little decay occurring at the ground level or to the portion lying below the ground. Some are still solid, but the concrete surrounding the post has broke loose and no longer provides support causing the post and panel to lean. Other times the post has completely rotted through at the ground level, again causing the fence to lean. The above examples can occur in both treated pine and cedar however, most often the posts that I have replaced that were cedar have had far more decay than treated pine post. This is upsetting for a couple of reasons.
The main reason is that a cedar post tends to breakdown much sooner than a treated pine post, at least for the portion that is in the ground. Cedar is a good wood, but it doesn’t handle direct contact with moisture over long periods of time. It’s not an exact figure, but for the projects I’ve been on where a cedar post was removed the general timeline was that the fence had been up 10-12 years. I’m sure some have lasted longer as well as shorter periods of time, but this has been the typical response I’ve received when I’ve asked about how old the fence was. The treated posts I’ve removed have been in the ground for twenty plus years. A rough figure we have to work with is that by using cedar posts we are only getting about half the life from the fence compared to what we would get by using treated pine posts. This doesn’t seem to be a good use of your home improvement dollars.
The other reason I find it upsetting is that it is a waste of resources. Usually the other components of the fence are still in good condition for their age. It is the failure of the posts that causes the problems. At least to my way of thinking it doesn’t seem to make sense to build with material that will break down sooner than a suitable alternative would; in this case treated pine.
Putting aside my own personal views of the matter; what is the take away for you for concerning cedar posts? I think the main thing to remember if you are considering cedar posts is to be aware of the likelihood for a reduced life span of your fence. The above photos are from three different projects, but they only represent a small sample of similar finding in other projects concerning cedar posts. Knowing this information will hopefully assist you in determining which approach will work best for you project.