Cedar fence posts instead of pressure treated?

RichZ · May 1, 2016

I put in a few dozen cedar posts on my old farm 15 years ago, they're all still solid with no signs of rot. Cedar is all I use now. It's also much easier to drill into for gate hinges and to nail fencing staples to.

oosik · May 2, 2016

I have 1 1/2 miles of five strand barbed wire fencing around my property. I've tried just about every type of post available and have come to the conclusion that soil type and moisture content are the biggest factors in post longevity.

Untreated Ponderosa pine will last 8-10 years. Treated(green color) posts will last 10-15 years. Heavy duty metal T-posts that were put in in 1892 are still very sound in some places. Likewise, there are about half a dozen cedar posts (Western Red Cedar??) well over 100 years old that are still good. I use those gooey treated railroad ties at several locations and they are as sound as the day I put them in 34 years ago.

My fence line goes thru a wet area and metal T-posts will completely dissolve at ground level in this 150 foot run within 6-8 years. The only posts that have longevity in this wet area are those gooey treated railroad ties.

The area I live in is considered semi-arid so most of T-posts will last well beyond 60-75 years - unless the cows bash them down.

MF283 · May 2, 2016

Back fill the post with gravel or sand & they'll drain better, last longer. Years ago i ran across a deal on some bucket's of roofing tar & treated the bottom 2' of the post. They are still good, i've had to replace some untreated ones that are in wet areas after 30 years, they are cedar, no complaint's here.
It's not everyday that we can get 30 years out of something:thumbsup:

Ronnie

GLyford · May 2, 2016

Next question...does anyone here put tar/roof sealer on at ground level?

dickfoster · May 2, 2016

ishiboo said:
I am looking to add about 2000' of fencing this year. My normal supplier of pressure-treated pine posts has discontinued selling them. They now offer only cedar. I found a supplier of higher-quality cedar posts as well, who is saying that the cedar posts last ~30 years... considerably longer than pressure treated posts would. I went with pressure treated because I had heard the exact opposite.

Will I be satisfied with cedar posts? They're about 30-40% cheaper than the pressure treated posts I can get my hands on.

It doesn't matter what kind of wood you use treated or not, cedar, redwood etc. etc. the moment you put it in the ground, that's any wood in the ground, the clock is ticking and you'll need to replace it sooner or later. Water eventually leaches out whatever is giving it its decay and insect resistance and it may as well be a piece of soft pine then. It doesn't help to set it in concrete either because concrete is like a sponge and the post will still rot out. If you keep the wood above ground by sitting the posts on top of concrete footers in brackets or use metal posts it'll last much much longer. It just depends on how many times you want to replace them. I've never seen redwood or pressure treated do much over 20 years in or out of concrete. When I do sit them in the ground, what I call a soft set post, I coat the wood going in the post hole in coats of roofing tar and plastic wrapping the bottom and sides exposed to the earth. Two or three coats of each will keep the water away from the wood thus the rot and insects for years and years. It's messy but it works, it doesn't cost much and you don't need the concrete. Either cedar or pressure treated wood set this way will last ya.

ishiboo · May 2, 2016

Thanks folks. The cedar posts are northern white cedar, and I am finding some data to support they last pretty long. Both choices are real round fence posts (which I believe are all heartwood), no square stuff.

I think if I could get 5 solid years out of them I would be more than happy... the eventual plan is to replace this particular area of fence with black chain link.

I won't be coating the posts, packing gravel, or anything time consuming... these will be pounded in as fast as I can put them in the ground.

dickfoster · May 2, 2016

Well if all you want is five years out of it, stick em in there. Even old peeler cores would probably do ya.

KennyG · May 2, 2016

Sounds like you have one of those jobs that just need to get done and you may get lucky and get years out of it. I had to replace a section of cedar split rail fence. The posts had completely rotted off. I don't know the age but I'm guessing over 20 years. I don't want to have to do it again, so I painted the in-ground portion with Rustoleum copper treatment, put 6 inches of gravel in the bottom of the holes and backfilled with gravel. I only did 5 posts, so it was no big deal. It would get to be a lot of work for a long fence.

Wagtail · May 2, 2016

I've gone around to every wood fence post and painted the tops of them to prevent water ingress... freeze/thaw and general water/exposure damage will cut down on their life expectancy just as much a soil rot.

I also purchased & installed purpose-made, UV protected, plastic post caps to every round post.