fence posts getting pushed up and out...

[danny burstein]

A couple of years ago we had professional installers install what's commonly called a chain link fence surrounding our yard 'cuz dog.

They dug holes for the posts, mixed up some cement, pushed the posts into them, then backfilled the top few inches with more soil.

Sure enough, the posts and their concrete bases have been creeping up and out.

Any suggestions as to how to fix this (presumably need to re-dig) and prevent the problem from recurring?

Thanks muchly.

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[RosemontCrest]

In what climate is the fence and how deep are the holes? Could freezing ground be heaving the posts? Perhaps a call to whomever installed the fence may provide some insight. Good luck.

[slate_leeper]

It may be the opposite problem. The soil may be receding exposing the bottom of the posts. I have had this problem, especially before I convinced my lawn service to NOT trim the grass extremely short next to the fence. Using weed killer along the fence line is another way to promote erosion.

-dan z-

[danny burstein]

[snip]

Thanks. I gave that some serious thought but some of the posts are close enough to the house that I could compare the height to the walls, and yeah, it's that they're coming up out of the ground.

And thanks to everyone for the other suggestions.

[Frank]

Also sounds most likely to me.

I did not have this problem with my old deck as described last year but new code required setting concrete post supports three feet below ground because of frost line.

I just found this on decks:

and assume it could apply to op's problem.

[Clare Snyder]

Don't say where you are or how cold it gets - or how deep they dug. Generally that happens when frost in poorly drained soil gets under a post that is not burried deep enough or the frost catches the side of the post and lifts it. Around here it is common to use SonoTube as a form and to bury the post 4 feet deep. Sometimes a "cone" footing is used to help keep the post from coming up as well. Even with ALL the precautions, it is almost inevitable that a post or two will STILL "float" to the surface eventually.

[danny burstein]

[snip]

Thanks again to everyone who wrote.

We're in a residential neighborhood in flyover country, with the temperatures about five degrees, on average, colder than, oh say, Chicago.

So yeah, lots of freezing.

The company that did the initial installation has been around for a couple of decades, so I'd have thought they knew about this issue...

Fortunately, we've still got another year or five before we "have" to address the problem.

Thanks again.

[dpb]

The other possibility is heavy clay soils with wet/dry cycles will act about the same as frost heave as they also expand when rewetted after drying out.

If the digging concentrated clay in some of the holes relative to others could explain differences between various post locations...or areas that were disturbed during house construction might have more clay brought up to the top levels.

--

[danny burstein]

Ahhhh, that's probably it. The "soil" here is just a couple of inches, sometimes less... of dirt and right below it is clay.

Causes all sorts of grief for plants and trees..

Thanks!

[Clare Snyder]

Good idea to ALWAYS put crushed stone about 6 inches or so feep in the bottom before the "footing" is poured