# The wrong way to anchor fence posts in concrete



## jjmartin1340

Some years ago, a friend was installing a fence. He dug holes 4 feet deep and anchored the posts in concrete. But first he put an 8" Sonotube (a heavy cardboard tube 8" dia., 4' long) in the hole. I had never seen Sonotubes used this way. He said it made the concrete with smooth sides, so when the ground froze and heaved up, it would not lift the post up too. Made sense to me. I never had to install a fence, so didn't know if it was really necessary. Found out last spring it IS a good idea. Saw a fence down the street where they had not used Sonotubes. We had a mild winter, lots of freeze-at-night/thaw-during-day cycles, and now some of the fenceposts are about 4" higher than they were. See photos.


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## BridgeMan

Classic examples of "junk" concrete work--improper consolidation, cracking, delaminations and missing (or incorrect) top-slope.  Sonotubes wouldn't have helped at all.

I've never understood why people spend good money on materials and then don't bother learning the proper basics of how to use them.


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## nealtw

This picture is a good sample of concrete not deep enough. The idea for concrete is to fill the gaps around the post so it drys firm to the undisturbed soil around it. If you use a sono tube you are then going to fill around that with dirt, what's the point.


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## CallMeVilla

While we are piling on (pun) where are the galvanized saddles for the posts?  If you are going to the trouble of sonatubes, why not install the saddles so you can easily replace the posts without having to destroy of the old concrete?

Get the guy who did this work on the phone and read him these posts  ....


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## Blue Jay

I don't understand using concrete to set a fence post, all my years on the farm we never did. Did not have any come out of the ground that were put in properly, even ones that had a gate hanging off it did not move. Guess people now days just don't know how to tamp the ground so the post does not move or don't want to put forth the effort.


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## nealtw

Blue Jay; I agree 100%, built lots with out concrete but after some people start sprinkling a little dust in the hole and the puplic is convinced it is the only way to go, the rest of us have to go along.
Villa: Have yet to see a saddle that will hold a six or seven foot panel fence.


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## CallMeVilla

Hey Neal  . . . strongest might be the carport saddle with rebar into the cement.  

http://www.strongtie.com/products/connectors/canada/rcps.html

Another version has two prongs that are pushed into the cement of the sonotube.


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## Wuzzat?

jjmartin1340 said:


> 4 feet deep
> now some of the fenceposts are about 4" higher than they were. See photos.


Is the frost line in your area deeper than 4'?


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## JoeD

Saddle would never hold up to the wind forces on a fence. Those things are only for decks.


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## jjmartin1340

"Is the frost line in your area deeper than 4'?"

This is Keswick, ON, Canada (north of Toronto).
Water pipes, etc must be 4 feet deep, so I assume the frost line is maybe 3 feet deep, probably less now with the warmer winters. The fence in the pictures is a couple of blocks away from me, don't know anything about it. I've been going for walks around the area for 5 years now. The fence was there when I started. It never heaved up until this spring, which is also the warmest winter in ages. Instead of -25C to -35C at night in February, we only had a few nights at -20C, and in March there were many days above 0C with nights -10c.


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## Wuzzat?

jjmartin1340 said:


> "Is the frost line in your area deeper than 4'?"
> 
> This is Keswick, ON, Canada (north of Toronto).
> Water pipes, etc must be 4 feet deep, so I assume the frost line is maybe 3 feet deep, probably less now with the warmer winters. The fence in the pictures is a couple of blocks away from me, don't know anything about it. I've been going for walks around the area for 5 years now. The fence was there when I started. It never heaved up until this spring, which is also the warmest winter in ages. Instead of -25C to -35C at night in February, we only had a few nights at -20C, and in March there were many days above 0C with nights -10c.


Thanks for your answer.

At my latitude/longitude the outside design temp is -10C/+14F so it maybe gets colder than that 1% or 5% of the time.

I imagine these kinds of temps can be dangerous if you are not acclimated.

Your freezing and thawing seems somehow to have compacted the soil more than it was when the fence was installed.


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## Wuzzat?

JoeD said:


> Saddle would never hold up to the wind forces on a fence. Those things are only for decks.


Yeah.
http://answers.yahoo.com/question/index?qid=20090624121616AAplSM3


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## nealtw

If your pipes are at 48" the fence wants to be a 48".
The fence coming out of the ground on a warmer winter will have more to do with the amount of water just below the concrete as compared to other years, warmer may have been wetter.


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## bemugg124

I think so, the concrete not deep enough


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## Wuzzat?

Assuming the posts were vertical when first installed, I'd think: 
-if the soil surface is sinking because of compaction the posts will still be vertical.  
-if the posts are being pushed up they should be becoming crooked, like old tombstones.


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## jjmartin1340

This seems to be getting a lot of interest. Here's 2 pics of the fence. It's becoming rather crooked from the post heaving.


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## nealtw

So the red fence was planted deeper.


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## Daryl in Nanoose

This has been an interesing thread, I just realized that the guy who used Sonotube has no problem with his fence but the guy who didn't has problems and yet everyone is picking on the guys who's fence is still good. Am I nuts here or??? Really not trying to make trouble here just not making sence to me


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## nealtw

Like Blue Jay said; we used to just tamp the fill back in around the post. If you use a tube, you are not filling the whole hole so your back to tamping the fill back around the concrete, so why bother with the concrete?
Any way if both fences were planted at the correct depth then both would have popped for the same reason, but the red one did not.


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## postanchor

Fence post holder, on one hand can erect wood post, meanwhile it's protect the post from corrosion, and replaceable if necessary. The real usage as follow: 
www.hsmetalproduct.com/product/post-anchor


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## nealtw

postanchor said:


> Fence post holder, on one hand can erect wood post, meanwhile it's protect the post from corrosion, and replaceable if necessary. The real usage as follow:
> www.hsmetalproduct.com/product/post-anchor



Is it your intention to hang around and offer suggestions when people need help or are you just spamming us?


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## CYUE

Blue Jay said:


> I don't understand using concrete to set a fence post, all my years on the farm we never did. Did not have any come out of the ground that were put in properly, even ones that had a gate hanging off it did not move. Guess people now days just don't know how to tamp the ground so the post does not move or don't want to put forth the effort.



See my photos attached, this is my situation. Two fence post are rotten at the base, need to be replaced. One attached to the wall, the other one will hang a gate. But these two posts are closed to the gas meter, and already located that gas pipe is under. Depth of post will be a problem for the one that hangs the gate. Any good suggestion in this case? Thank you.


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## zannej

I know that my father probably didn't sink the wooden fence posts deep enough. I think he only dug about 2ft down but I can't really remember for certain. They posts didn't come up though, but they rotted above the ground level (even though they were pressure treated) and broke off. Some came loose and can move but didn't come up.


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