Fencing brace-post pulling up during install ... Suggestions?

[beppington]

Since Red Brand's installation videos say to do it this way, in the beginning we had the "TEMPORARY 4x4 HORIZONTAL BRACE" higher than the "PERMANENT 4x4 HORIZONTAL BRACE", so it was higher than the fence wire & therefore out of its way, but when the left brace-section post started coming up, we thought the "TEMPORARY 4x4 HORIZONTAL BRACE" was pushing the top of the left brace-section post to the right too hard, making the left brace-section post sort of pivot around the "PERMANENT 4x4 HORIZONTAL BRACE" ... so we lowered the "TEMPORARY 4x4 HORIZONTAL BRACE" to be lower than the "PERMANENT 4x4 HORIZONTAL BRACE" & re-tensioned. Again, it helped, but the left brace-section post still wants to come up.

The entire fence length is 1,315 feet, and this problematic brace section is at about the 1,150' mark, meaning we're almost at the end. So ... I think we can live with this "almost tensioned enough" section if we have to. What really concerns me is that there's only on more brace section to go ... The End one :shocked: If the final post(s) wants to come up/ out, there's no more additional fence beyond it that we can rely on to counteract the pulling to the right ... So we gotta get that one solid on its own.

At the fence end, I think I'm going to add a second brace section so I have two brace sections in a row, & install both the red & blue criss-crossing wires on both sections. I wish I had concreted these last two or three posts in. Maybe I should pull 'em up & do that ...

Wow ... Long thread for a little fence post pullin' up situation :laughing:

 

[BeeferMan]

I do see what you're saying. But still, the pressure won't go away, though it will be distributed from top to bottom. Bottom line is that everything thing is braced properly. I would re-tamp both of those brace posts. If either one moves, you'll get heaving posts.

Right, absolutely - the tension never goes away, that's what keeps the fence tight. All you can do is try to distribute the forces equally and transfer them as much as possible to an immovable object. In this case the "immovable" means applying the force horizontally at the ground level of a buried post.

But let's also remember this is also the ideal scenario, where everything is flat and level. A slight rise of elevation to the right of the diagram can really throw a curve ball at this. Ask me how I know...

 

[BeeferMan]

Wow ... Long thread for a little fence post pullin' up situation :laughing:

He he.. It ain't rocket science, but it ain't always obvious either. Took me a while to get it through my head that when it comes to fencing, a little extra work at install time pays off in the long run... :thumbsup:

 

[beppington]

I had that happen with railroad ties used as fence post, and did not understand it at that time.

The brace post should be braced against undisturbed ground. Could also add a 12 in long and 2 x 6 in wood bottom brace vertical in the hole for the brace to butt against.

I think I see what you're saying ... Jam a piece of wood in the post hole between the post & undisturbed ground. That would probably help. In the end, I suspect that if I poured in concrete instead of just tamping the dirt real well, I could probably tension the wire with just about all my might.

 

[MMagis]

But let's also remember this is also the ideal scenario, where everything is flat and level. A slight rise of elevation to the right of the diagram can really throw a curve ball at this. Ask me how I know...

Yep, I know hills pretty well too.

 

[zzvyb6]

Actually, it IS rocket science. You need to do a moment balance around the main post at ground level. Then you will see that there is nothing counteracting the MOMENT created by the wire force times the distance from the top of the post to the ground. To counteract this moment you need a diagonal to push or pull against the top of the post. You can't push on a wire but you can push on a post (or actually a 4x4) set from the base of the 2nd last post to the top of the last post. OR, you can set another post and tie a wire from the top of the last post to the base of this temporary post (or stake). Otherwise, all you've done is created a solid square structure that can 'match-box'. Sort of like a table that you can tip over by pulling from the top. You need to use a counter measure to resist the tipping force. This tipping force can NOT go thru the last post at ground level.

Draw a 'free-body' diagram and that will show you what I mean.

 

[MMagis]

Actually, it IS rocket science. You need to do a moment balance around the main post at ground level. Then you will see that there is nothing counteracting the MOMENT created by the wire force times the distance from the top of the post to the ground. To counteract this moment you need a diagonal to push or pull against the top of the post. You can't push on a wire but you can push on a post (or actually a 4x4) set from the base of the 2nd last post to the top of the last post. OR, you can set another post and tie a wire from the top of the last post to the base of this temporary post (or stake). Otherwise, all you've done is created a solid square structure that can 'match-box'. Sort of like a table that you can tip over by pulling from the top. You need to use a counter measure to resist the tipping force. This tipping force can NOT go thru the last post at ground level.

Draw a 'free-body' diagram and that will show you what I mean.

You're over thinking it. Fences have been braced like this for as long as fences have been built. Keep looking at it and you'll see why it works. It's all there.

 

[SandburRanch]

For this problem post, drive a T-Iron post at 45ｰ (that's 45 degrees) down 5 ft. as a dead man and twist a brace wire from the bottom of the dead man to the top of the heaving post. In the pic that would be to the left. On some long sections a double dead man may be required. One for the corner post and one for the brace post.

When you get to the last set of braces do the same even though one dead man may be on the Doberman's side.:laughing:

 

[nwbearcat]

I'd guess posts not tamped as good as they need, or as deep as they need for that span of fence. Growing up, never got to leave the post unless we ended up using ALL the dirt dug from the hole to fill back in around the post. We tended to use 10'+ posts, 5' in, 5' out for the 1st post in the line, maybe a smaller one for the 2nd brace post. You're alot tougher on a set of digger handles than I if you can dig them faster than the Danuser...

Smooth posts will pull worse than the hedge posts we used, might consider driving a spike through them in a place or two.

Other thing I'd say is brace maybe not as long as it could be. Steeper brace wire tends to pull post worse.

Never went to the effort of setting another post to pull out just to stretch the fence with. When we ran woven wire, used a pull board like you have. We'd hook the 8n Ford on the wire, and in 1st gear at a low idle, would let it pull until it spun or died. Then we tied off the fence. On flat ground that was about right, had to leave more slack on hills.

Didn't read all of this, but might help you some:
http://www.mbforagecouncil.mb.ca/Fo...acilities/10-6 Brace assemblies-BC Agric.pdf

 

[3nickles]

I know what is happening, only because I had the same problem.When tensioning ,go slow. Tension about half then wait for the "wave" to settle down.You are pulling on a spring and if you pull too fast the tsunami hits the other end with a multiplied force.Remember there is something as too tight,you only want to take out half of the kink found in the horizontals.The compresion brace is prettier horizontal but is usually only used when you have too because of through drilled wires.It will work better if the compression is directed to the ground.or for excample at the last post from the top of last to bottom of second last and mid braces would need two from the centre top to the bottom of each next post.Hope this helps.