New privacy fence bowed down from wind

[jim44]

I was going to go with the holes just need to be longer, but it looks like the posts can't go any deeper due to the height of the fence. Sounds like you did everything right.....

 

[ishiboo]

I would have set the posts in gravel.

How big are the holes you augured? Where did the concrete go, at the very bottom?

 

[Coyote machine]

Sounds like you have a couple of things going against your project. I had pros install a custom solid PVC fence at my CT home. They had to hand dig out each post hole. They reinforced about every fourth 'post' with a metal pipe, and concrete in each hole.
If you can reset the fence without taking it all apart and redoing the posts, I'd be inclined to do so and stabilize the fence with bracing until the ground freezes solid. You may be able to save the project without tearing it out and redoing it all. The fact the ground is soaked makes it near impossible for the fence to resist heavy wind. Once frozen it may stabilize, and if not come spring you're where you are now anyway.

Ideally you would only dig a hole slightly bigger than the post diameter/width, and for sure have it pushing against the side of the hole against the prevailing wind, so it uses the solid earth to support the post against shifting. This seems less likely to be able to be accomplished due to the ground saturation and having drilled 12" holes.

Show us some pics of the sag/bend of the fence so we can access the situation....

 

[ishiboo]

Ideally you would only dig a hole slightly bigger than the post diameter/width, and for sure have it pushing against the side of the hole against the prevailing wind, so it uses the solid earth to support the post against shifting. This seems less likely to be able to be accomplished due to the ground saturation and having drilled 12" holes

No, if you are using concrete or gravel a larger hole is necessary because the concrete/gravel can then distribute the forces over a larger soil surface area. The mass of the concrete or gravel also acts to hold it all together, of course, so the larger the hole the more benefit you get from that. The only time you really want a hole slightly bigger is if you are replacing the soil, since it is difficult to meet the original compaction and you would have a lot more to do. I have a 5' wire fence around about an acre that I drilled, and even compacting the holes again in layers they move around much more than the posts that I pound with the post pounder.

 

[Coyote machine]

No, if you are using concrete or gravel a larger hole is necessary because the concrete/gravel can then distribute the forces over a larger soil surface area. The mass of the concrete or gravel also acts to hold it all together, of course, so the larger the hole the more benefit you get from that. The only time you really want a hole slightly bigger is if you are replacing the soil, since it is difficult to meet the original compaction and you would have a lot more to do. I have a 5' wire fence around about an acre that I drilled, and even compacting the holes again in layers they move around much more than the posts that I pound with the post pounder.

I didn't say anything about using concrete or gravel. What I said was to use a small hole so the existing (compacted ground) would support the posts. The large hole with gravel/concrete is not working so well, or the problem wouldn't exist. The ground is offering no support because it's saturated and cannot resist the flag effect of the wind pushing on the fence sections, moving the posts which are not secure in the ground. Until the ground hardens that fence will move at will regardless of how deep or wide the holes are and how much gravel, concrete etc. are present. YES.

 

[AchingBack]

Post holes should be wider at the bottom, like a bell shape. A straight shaft will be weak and eventually fail.

 

[ishiboo]

I didn't say anything about using concrete or gravel. What I said was to use a small hole so the existing (compacted ground) would support the posts. The large hole with gravel/concrete is not working so well, or the problem wouldn't exist. The ground is offering no support because it's saturated and cannot resist the flag effect of the wind pushing on the fence sections, moving the posts which are not secure in the ground. Until the ground hardens that fence will move at will regardless of how deep or wide the holes are and how much gravel, concrete etc. are present. YES.

If the ground is so saturated it cannot support the post, something needs to be done to change that situation... which means sinking the post deeper or increasing the surface area/mass of the anchor. Either way, hole is going to have to be bigger to handle this. With only a single bag of concrete per hole, the replacement hole is going to have to be quite a big bigger than it is. Sorry, that's simply how it works.

 

[Mace Canute]

Post holes should be wider at the bottom, like a bell shape. A straight shaft will be weak and eventually fail.

Where did you get that recommendation from? I'm a Journeyman Lineman having worked on both distribution and transmission crews for 2 decades for the provincial electrical utility and have set more 35 to 85 foot poles than I care to remember and I've never heard of that.

 

[ishiboo]

Where did you get that recommendation from? I'm a Journeyman Lineman having worked on both distribution and transmission crews for 2 decades for the provincial electrical utility and have set more 35 to 85 foot poles than I care to remember and I've never heard of that.

I think it's a legitimate concept but not for the reasons he thinks. It relates to concrete-poured posts and weight-carrying piers. A concrete-poured post with a wider spot of concrete above the frost line gives something for the frost to "grab" and pull up, so the general rule is to have them bigger on the bottom, below the frost line, to prevent uplift. It has nothing to do with "strength".

Weight-carrying piers, of course the wider the bottom the more distribution of weight onto the native soil.

 

[Mace Canute]

I think it's a legitimate concept but not for the reasons he thinks. It relates to concrete-poured posts and weight-carrying piers. A concrete-poured post with a wider spot of concrete above the frost line gives something for the frost to "grab" and pull up, so the general rule is to have them bigger on the bottom, below the frost line, to prevent uplift. It has nothing to do with "strength".

Weight-carrying piers, of course the wider the bottom the more distribution of weight onto the native soil.

Yes, I'm quite aware of the reasons for a bell bottom for poured concrete piles and even preformed ones but for wooden poles all I've ever seen are straight sided holes, even for the ones for the preformed bell bottom piles. It was common practice to install concrete "buttons" under the wood dead end poles to help prevent the poles from settling due to the vector forces acting on it from it being a dead end.