Should I concrete the fence posts or not

[ray66v]

If you notice the fence posts that you see where the cement popped out of the ground, besides not being set deep enough, the most common reason is, they ran the cement all the way to the top of the hole. Leaving room for dirt, at the top of the hole (4" to 6") is a good way to help prevent this from happening.

With chain link fence, (because you have to stretch it), I cement the ends and corners, and drive the rest. In our area, for ends and corners, I dig 24", drive the post another 12" and cement in place. On the rest of the posts I drive 18".

 

[Highbeam]

The typical excuse for the 18" depth is that the fence boards are 6 feet tall, the posts are 8 feet tall and you need a little gap below the fence and the posts need to stand proud of the top. 18" is fine for privacy type fence in my climate with concrete, not fine without and not fine for livestock applications.

My latest fence was a 4 foot tall 3 row horizontal board fence. and I sunk those 8 foot posts as deep as the auger would go for about 3 foot bury and then used an 80# sack of dry concrete mix in each. Put the post in the hole, throw some dirt or gravel in there and then to the top with the mix. Water the dry mix to wash it off the post and to allow forming of a mound around the post and then go to the next one. I cut the tops off after the fence was built.

Go deep and use concrete.

 

[gordon21]

Depending upon cost/time concerns, you might want to consider a combination of designs. Every third or fourth post goes extra deep with more concrete and you can then still run the other posts a little shallower. Keep in mind that all corners and gate posts will need far more support.

 

[patrick_g]

Any fence post put ONLY 18" into the ground...you'll be able to push over by HAND in 2 years time

Welded pipe fence lets adjacent posts help support each other.

Still, when I do it, I auger down and bury 2 1/2-3 feet. I prefer to use a 12 inch auger instead of 9 or 6 inch. I often put 2 bags of post crete into the bottom of the hole, add water, rod it a bit, and backfill depending on circumstances. You can skip the water if you don't care how long it takes to cure and one bag would probably be enough but I tend to go a little extra and be sure. I do not fill the hole to the surface with concrete. I end up with a concrete "anchor" at the bottom of the hole.

The fence guy (40+ years experience) who taught me said when you concrete to the top of the hole there is no dirt over the cement to offer resistance to frost heave or other forces. My experience has been that concrete all the way to the surface doesn't resist being pushed over any more than and perhaps less than just doing the bottoms.

Another plus of putting in the post crete dry and not wetting it is that all the little motions you make fussing with the posts while continuing the job (welding, grinding, clamping, fitting, and whatever) can move the posts a bit and if the crete was wetted and started to set up you break the post's contact with the crete and have a weak connection. Placed in the hole dry, the concrete will not cure for a while but rest assured unless you have desert dry soil, it will cure.

Pat

 

[tsterkel]

North Texas Blackland Prairie here. The advice on 80 pounds concrete every hole with expansion pipes is spot on. We have a lot of pipe fences around here that were put in without concrete, and after the 3 year drought are leaning enough that I can use them for a step.

 

[Tractoringaround]

I am building a pipe fence for about 8 acres. I have been told by some people to use the auger on the tractor and dig the holes then set the posts in conrete. The posts are going to be 4 1/2 tall and buried in the ground about 18 inches. I have also been told that if I drive the posts in the ground 18 inches then weld the pipe top rail on the fence it will not have to be concreted in the ground. If at all possible I would love to do it without having to concrete the pipe in the ground, because that saves money and work. Some say that when it is welded together it will be strong enough not to move when a horse leans on it. Any comments would be greatly appreciated.

I asked the same question some time back. I tried packing the posts with dirt and do not feel it is the best way to go. Now I set all my post in concrete. The holes I dig are with a 6 inch auger close to 2 ft deep. I mix my concrete on the dry side, never runny, in the tractor bucket, shovel it in the hole around the steel posts and pack it real good with the end of a 7/8 inch rod. If you do it with concrete you are also protecting the post. I figure I do not want to be out there redoing posts when I am 85! I also was wanting to save on money and work and have found the concrete is really not costing that much. Once I got a good system going it is not that hard to do and quicker than packing with dirt. Like yours, my fencing is also for horses. They scratch themselves on it and it is holding up fine.

 

[jnealhicks]

Something I never see addressed here--perhaps because it won't work or isn't needed--is the idea of adding something, a t-post, for example, as a kind of mast to help keep the fence straight. I know it doesn't look the greatest, and would have to be on the outside, so livestock wouldn't be injured by it, but if you took an 8-10 foot t-post, and buried it 5 feet or so straight down, immediately adjacent to the post, and repeated that, say, every 5th post or so--would that help keep the fence straight??

 

[sweettractors]

When I have bought farmland, The posts set in concrete are rotted out starting at the concrete. Usually these posts have been in for 15+ years. Good Kentucky Red Cedar or Locust will last 30+ years in dirt. Ken Sweet