Hi! We have a 6ft vinyl privacy fence that we need some advice about. We have poor draining soil and we get a lot of high winds in our area. After a storm with heavy winds there is water that sits around the concrete that has been poured at the posts and the fence leans. We took down one whole section last year and reinstalled it in hopes that using different concrete would help but no such luck. We have had several storms since and now the entire fence is a hot mess. Is there a different kind of concrete or installation method we can use to help with a soil that doesn’t drain? Thanks!
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Please describe how big a hole and how much concrete you are using? How deep ?
In some cases an elongated hole perpendicular to the run of fence can work better at resisting the forces against the fence. Tamped stone, concrete if you wish with some rerod. Horizontal rerod, tied to the post, long with the elongated hole.
Hi Calvin,
I don’t know for sure on the info since I didn’t actually do the work my husband did but I did assist. We rented an auger to drill the holes and I think we went down over 2-3’ and the opening was approximately 18” wide before we set the post. We used quick setting concrete and it took about 3 bags per post. There is a hole in the bottom of each post for the concrete to flow through which is supposed to help hold the post when it sets. But with all the water retention it’s like the concrete is separating from the post. Very frustrating.
How deep are your posts in the ground? You really can't put up 6' fence on 8' posts. Where are you located generally?
florida, fences up north are mostly 6' on 8' posts. Three feet are in the hole and five above ground. The top cross rail is 5' above ground and the pickets extend a foot above the rail. They generally don't blow over, but we don't have hurricanes other than the remains of one occasionally. My fence has survived 75+ winds perpendicular to it.
I've run countless miles of fence and taken down even more. My experience is that 90% of all 6' fence has posts 24" or less in the ground. I've seen posts 6" in the ground. I use 10" posts and put at least 42" in the ground with, nowadays, foam to within 6" of ground level. Even here in sandy south Florida they rarely lean.
You can get away with 2 feet of post in the ground - but it's more about how far the concrete goes down. For aluminum posts - our suppliers say to dig the hole a foot deeper - add gravel - then the post and cement. This should allow some drainage and keep the posts sturdy.
I am in central Indiana and our home is built on what was a corn field. The ground is hard and the water stands after a rain. I’m not sure about the depth but we rented the auger and we drilled the entire depth so I assume it is at least the 3 feet. Just not sure why the concrete isn’t sticking to the posts. We can literally pick these posts up out of the ground with the concrete attached on some of them after a rain if we had enough muscle. On some of them the concrete has cracked and you can see water just sitting in the hole.
Water in the hole? It's not draining? Is your soil clay? Sounds like expansive soil to me.https://en.wikipedia.org/wiki/Expansive_clay
I would say it is clay soil. We installed the fence during the summer and it was dry and hot as satans den and we broke two drill bits just trying to get the holes dug. We have a hard time even growing grass in some parts of our yard. We paid quite a bit of money for the fence material and want to be able to fix it ourselves if possible. Thanks.
You might be better off with gravel rather than concrete. Expansive soil can be a major geotechnical nightmare.