Lifespan of a fencepost?

[56FordGuy]

About two years ago, we had roughly 4 acres fenced with treated wooden posts, roughly 4x4", with rounded corners like landscape timbers. The holes were dug, and the posts were set in packed dirt. The field was empty for about a year and a half, and has had two horses in it for about six months. We checked today, and in that one field have 35 fenceposts that are either broken, or weakened to the point that lightly pushing on them with one hand causes them to start leaning and audibly cracking. Is this normal? At the time, we were assured the posts would be 'just fine' set in dirt, because they were treated and the dirt would be hard packed around them. Unfortunately, I don't really think 35 of them needing to be replaced after two years is 'just fine', but that's why I wanted to ask y'all. About how long should a wooden fence post last?

 

[clemsonfor]

About two years ago, we had roughly 4 acres fenced with treated wooden posts, roughly 4x4", with rounded corners like landscape timbers. The holes were dug, and the posts were set in packed dirt. The field was empty for about a year and a half, and has had two horses in it for about six months. We checked today, and in that one field have 35 fenceposts that are either broken, or weakened to the point that lightly pushing on them with one hand causes them to start leaning and audibly cracking. Is this normal? At the time, we were assured the posts would be 'just fine' set in dirt, because they were treated and the dirt would be hard packed around them. Unfortunately, I don't really think 35 of them needing to be replaced after two years is 'just fine', but that's why I wanted to ask y'all. About how long should a wooden fence post last?

Those things for some reason dont last long? I think there marginally treated for above ground, ground contact. I have some around my house that are pretty rotted forbeing treated. True 4x4's should easily last 20 years but a good cedar, locust or osage post will last a lifetime. Dont use those landscape timbers anymore. Use a cedar post every 3-4 posts or a 4x4 and then use metal t-posts inbetween, they will last a long time and you wont have to did a hole.

 

[magicheater]

A lot depends too on the humidity of your climate. I lived in Idaho when I was a kid and posts did not rot because it was so dry. The preservative is another factor. I have recently salvaged 6X6's here in Wisconsin that have been in the ground for 40 years and appear to be as new as the day they were put in. Using them in various projects now. Creosote was the preservative but has since been outlawed except for the utility companies, go figure.

 

[56FordGuy]

Those things for some reason dont last long? I think there marginally treated for above ground, ground contact. I have some around my house that are pretty rotted forbeing treated. True 4x4's should easily last 20 years but a good cedar, locust or osage post will last a lifetime. Dont use those landscape timbers anymore. Use a cedar post every 3-4 posts or a 4x4 and then use metal t-posts inbetween, they will last a long time and you wont have to did a hole.

We had a contractor put this fence up for us, and he selected the materials. I wasn't thrilled with the job when it was done, but had hoped it would last. Unfortunately, it looks like I'll be redoing a lot of it myself anyway. Should have done it myself to start with, but couldn't make the time to work on it.

I wasn't sure about using the timbers the first time, but was assured that they would be fine. No such luck. Looks like I'll be driving T posts and hand digging some post holes before too long.

 

[300UGUY]

A lot depends too on the humidity of your climate. I lived in Idaho when I was a kid and posts did not rot because it was so dry. The preservative is another factor. I have recently salvaged 6X6's here in Wisconsin that have been in the ground for 40 years and appear to be as new as the day they were put in. Using them in various projects now. Creosote was the preservative but has since been outlawed except for the utility companies, go figure.

I have some posts that are in very sandy soil, on a hill. They are in very good shape, after 30+ years. Same fence, down in the swale, the same posts didn't last 10 years. They were wet pretty much all the time, never got to dry out. One other thing, the top was solid down to 2 inches above ground, and the bottom was solid deeper than 4 inche or so. A 6 in piece right where ground and air come together was where it rotted off.

 

[RickB]

Species selection is important. For example, untreated Lucust will last 30-50 years in many situations. Of course after a couple years you need to drill holes for nails & staples.

 

[teg]

...fenced with treated wooden posts, roughly 4x4", with rounded corners like landscape timbers...

"Like" landscape timbers or were they actually landscape timbers? Those are not really made for direct burial. I think they are treated to 0.25 where normal pressure treated is 0.4 and marine grade pilings is treated to 0.8

 

[Jim Thompson]

Pressure treatment does not prevent wood from rotting under the right conditions. They are normally only treated to prevent damage wood destroying organisms- bugs. Now if creosote were still available, that's a different story.

Jim

 

[ridger]

i have 50 acres that has been fenced and cross fenced using treated 4x4 post and have had very little trouble.its about 25 to 30 years old.the soil is real sandy.i also have frontage road 1000+ feet all treated wood but i cemented the posts in and have never lost one.-+

 

[trailbuilder]

Landscape timbers here are made from Aspen which is very non decay resistance (rots quickly) They are the cores from making aspen plywood and that is why they are cheap. Other areas might have pine landscale timbers.