View Full Version : Clay Soil Rant!

Jan. 28, 2009, 11:23 AM
Do any of you have to deal with clay soil? I am so frustrated and I am not sure if we can do anything about it..

Clay soil contracts and expands so much that it is impossible to keep the 4x4 (concreted into the ground) fencing posts standing up straight. When it rains torrents, the posts get loose and then all it takes is a horse to bump or kick a post for it to move. Unless we get out there and get the post back into line before the ground dries up..it resets itself and parts of the fence look terrible. We have tried to string a hot wire and that did help - it stopped any butt/body rubbing, but did not get in the way of any horsey quarrels. After a post has been moved a few times, the concrete it is set in starts to break apart.

We have been thinking about replacing our wood fence with PVC in certain areas, but honestly, I am afraid that since the PVC slats are 'connected' inside the 4x4 - if this same scenerio happens with the PVC, it would come apart and the horses safety would be compromised.

Any ideas?

Jan. 28, 2009, 11:35 AM
My husband and I bought 28 acres and there was only one place that perked for a house site, the rest is gray clay and not buildable at all. The property floods during rain and is hard as a rock when it dries out.

However, we do not have a problem with the fence posts. The first paddocks were put in by a fence company and the last field we put the posts in ourselves. No problems and its been 2 1/2 years. Posts need to be in 3 feet minimum, most of ours are more. Are your posts in the ground deep enough? Are you tamping the ground after you set the posts? We also put the corners in cement and used very large oversized posts for the corners. Are you using 16 foot boards, these stabilize the posts.

Hope this helps. . .

so, after rereading yor post I see you are using 4 ft posts????

Jan. 28, 2009, 11:50 AM
When you set your 4x4 you should tamp crush and run gravel in at the bottom at least 12" and then backfill with dirt for the remaining 2 feet. If your 4x4's are treated you should never use concrete as it will cause the posts to deteriorate at a very fast pace. Use 6x6's for your corners and gates (also with crush and run).

If you have posts working loose after your fence is up, use a tractor/comealong to pull it carefully back into place, then tamp and add crush and run at the top and tamp hard. The gravel will set up and help hold the post at the top.

Also, don't forget to brace your corners and at mid points along your fence line - We used diagonal in the corners and midpoints and then horizontal braces at any other potential problem areas/hills.

Jan. 28, 2009, 11:51 AM
so, after rereading yor post I see you are using 4 ft posts????

I think she means 4x4 posts but they should be 8 ft long

Jan. 28, 2009, 11:55 AM
We did not use 4' posts...I think you misunderstood when I talked about the posts being 4x4's.

We hired out the job - but I know for sure the 4x4's are not in that deep. They are down 18"...so in there lies the problem! Thank you so much though - at least this give me hope of being able to correct the problem and later what we need if we do the PVC fencing.

You guys are great!!!

Jan. 28, 2009, 01:08 PM
We live in a heavy black clay soil. All fence posts are at least 2.5 ft in the ground with sackcrete around them. We've gotten really good with the sackcrete. Put some water in, add 1/2 sack or so and use a metal bar to mix it, add more water and more sackcrete up to the ground level.

Right now we're in an exception drought (that's worse than an extreme drought). The fence posts that my Dad put in over 20 years ago are coming out. It takes some extra effort but they do stay put.

Jan. 28, 2009, 01:08 PM
yeah, what KnKshowmom said.

Get thee some gravel ;)

Jan. 28, 2009, 10:43 PM
OK fence post fans, I have a question. After pulling and replacing several 12 year old broken posts this summer, in clay mix, they were ALL solid at the base (30" down) but rotted at ground line and down 12". So, for the new ones, I tamped dirt up to 12", then concreted from there up to ground level with a raised cone around post a bit above ground level.

These are 6" round treated posts. Do you think they will last longer?

Jan. 29, 2009, 02:23 AM
When you set your 4x4 you should tamp crush and run gravel in at the bottom at least 12" and then backfill with dirt for the.....

To prevent confusion, I think he/she is referring to "crusher run gravel".

I put line posts at a minimum of 30" (2 & 1/2 feet) deep. I use nine foot corner posts and place them 4 feet deep. A PTO driven post hole digger is great help, and posts at that depth will stay put.

Jan. 29, 2009, 09:13 AM
We have very heavy clay as well. In our area is is commonplace to pound (not auger/dig) fence posts in because of the clay. We had new fencing installed last spring and I believe for our 4' tall sections we have 8' locust posts pounded to about 4.5-5' deep (so at least 3' deep) and then angled off.

But I know what you mean. The old fencing we still need to replace gets more and more crooked every spring with the freeze/thaw cycle. I think those sections were dug because they are only about 2' deep. I always worry that I'll wake up one morning and find some of it laying flat on the ground.

Good luck!

Jan. 29, 2009, 09:57 AM
We did the sackcrete thing also for each post. They've been in 15 years and still look good.

Jan. 29, 2009, 11:23 AM
We have another section that we had the post driven in and they are very tight but not always straight if you have a lot of trees/roots. The guy who planted them for us then wasn't available plus the ground was rock hard from the drought so we drilled them ourselves - took forever!!

If you don't have root/subsurface rock issues a driven post in clay is the way to go!

Jan. 29, 2009, 11:24 AM
To prevent confusion, I think he/she is referring to "crusher run gravel".

Yup, my bad! :yes:

Jan. 31, 2009, 09:50 PM
In this part of MS we have a lot of "gumbo" clay soil. It has no bottom and a huge shrink/swell capacity. It's wet, wet, wet in the winter and hard as concrete in the summer. I have crawfish living in my pasture soil.
Any homes not built on sufficient "red dirt" foundations will settle and crack. Pretty much all the homes I looked at before building had settlement issues.

That said, the wooden posts are 2' deep in concrete - of course, down here you can do it the "southern way" - dig the hole put a little dry quickcrete, the post, more dry quickcrete and fill with dirt. Let sit for 1 week before stringing fence. Those posts will be set solid. No need to add water. :eek:

I was really surprised when I saw it done that way, but my BF is a local, and he said they always do it like that down here. Lots of other folks said the same.

The only posts I'm having some trouble with is T-posts. A few are in the wettest areas and are leaning a bit this year. We've had a lot of rain this year!

Feb. 1, 2009, 09:05 AM
you may also try have the posts pounded vice in a hole. It seems to be much sturdier (and faster to install....)

Feb. 1, 2009, 02:11 PM
Yes, I think installing might have the same problem unless you find the proper way to install posts in your area. Saw a PVC installation in Oklahoma that was held together with
baling wire as the posts had shifted all over the place. It was pretty pathetic looking.

Check with local farm fencing installers and see what they recommend, even ask if you
could drive by some of their work. If there are any public facilities, find the manager and
ask who did their fencing and how long ago.


Feb. 1, 2009, 07:49 PM
This "post pounding" always amazes me. I am used to a tractor mounted auger that produces a high shine in the bottom of the hole. Must fill hole with water and soak overnight to get deep enough.

Feb. 1, 2009, 08:10 PM
I am on clay and had round posts driven in, 14 years ago and they are still very firmly in place.