Eastern Red Cedar for Buried Posts

The heartwood of Eastern Red Cedar has better rot resistance than the sapwood has. January 18, 2011

I've been told that by sawing eastern red cedar into posts that it will not last long. I've used cedar posts in fences all my life with no problems. I'm now in the process of building my shed to cover my mill and I'm looking cedars to saw into 6x6's for the corner posts. I know of other people that used cedar for this and had no problems. Has anyone had problems with cedar?

Forum Responses
(Sawing and Drying Forum)
From Gene Wengert, forum technical advisor:
The sapwood of ERC does not last. I suspect that someone has received the information that second growth species including cypress, WRC, and redwood does not have the decay resistance of the original or virgin growth. This person then applied it to ERC, but I have not seen such information about ERC. It may be true or may not. So, when using ERC posts, one might be very cautious and not do it any more if a broken fence post would mean a large loss risk. The alternative is to use properly pressure treated (ground contact and certified) SYP. Note that there are several treatment chemical options for commercial use

From contributor G:
I made some raise beds from green DF, after my wife purchased some graded lumber and built herself one. After four years we moved the beds. The graded lumber was almost totally gone. The green DF still looked good. I don't know why it held up better, but one difference is the DF was green at the start. There is an old saying you should build your boat from green wood because the wood will last longer. Many commercial fishing boats are coated on the inside regularly with saltwater to protect the wood.

From Gene Wengert, forum technical advisor:
I wonder if the difference was heartwood versus sapwood.

From contributor A:
Iíve used ERC several times for ground contact corner posts in buildings. I have experienced no problems. Make sure to remove all of the white that you can.

From contributor X:
My experience has been that peeled posts will rot but all-heart posts will not rot. If you ask ten ranchers here if they like ERC for fence posts half will say no half will say yes. When you ask the ones that don't like it if they used peeled posts or sawn all-heart posts they scratch their head a second and usually you don't even have to say anything else, you see the light bulb come on. ERC sap has no resistance to rot and once the rot starts in the sap for whatever reason it continues into the heart unabated. But with all heart the rot does not gain a foothold for some reason.

I did see a situation where a guy down the highway a piece had installed all-heart posts that rotted out in about five years, but it was in a flood plain so it would stay wet half the year then go to the other extreme of drought. I suspect this opened up the wood fibers to the point it could not resist the various fungi etc. and succumbed. Otherwise, if allowed to drain properly the wood will last many years. They will not last nearly as long as Bois d' Arc but what does. There are Bois d' Arc fence posts here 100 years old and better.

From contributor K:
I use ERC all the time for post and have some that have been in the ground for 40 years. The best trick is to char the end of the post and pack them in gravel. Do not use concrete to put them in. Crushed stone works great. Removing the white sap wood is a good thing but most good 6x6 posts will be all heart, the bottom part of the post anyway.