Fence post bracing

[Bruce]

So I guess I'll need to increase the the size of my rock surfaces. That should be fun now that the fence is stretched. I have a floating brace at both the NW corner (the one that is 2' down and concreted) and the strike post for the gate (in the west fence line). I used large rocks fairly flat on 1 side. About 8"-10" by maybe 14"-18". Also, I used 6" posts not 8".

 

[greybeard]

The numbers I used were just examples--there's no specific sizes required or 'formula'--you just need the soil under the rock/slab to roughly be able to carry the same load a vertical brace post would in an H setup since that diagonal post and slab is taking the place of the H's vertical race post.
Your 24" deep 6" anchor post is presenting 144 sq inches of surface area.

About 8"-10" by maybe 14"-18". Also, I used 6" posts not 8".

Taking the middle number (9"x16") you provided 144 sq inches of resistance at the slab, which is exactly the same as your anchor post.

Now, whether 2' deep is enough is a different question--it won't work in my area and my soil type, rainfall, and brahma influenced cattle pressure, but might work fine in your application and needs.

For here, deeper is always better..3'-4'.

 

[Bruce]

Yeah I know but since I don't have a jackhammer I had to stop at the ledge 2' down. BTW thanks for the diagram and calculations. Very nice.

BTW, don't know if you saw this on the other thread @greybeard

These are the things that make my fencing job more difficult. Top of that rock is 2' down, I don't even know the extent of it vertically nor to the north (up in the picture) and east. This hole was supposed to be the gate post in the west fence line. The post was supposed to be centered ~ 5" from the top of the picture based on the strike post hole (which was dictated by a rock I hit). I dug the strike post hole first and when I hit this I dug the brace post hole THINKING that it was a rock I could get out. That was when I had a ~10" diameter hole. So I had to dig 3 new holes when I determined there was no way *I* was getting this rock out and dug the 3' hole for the gate post on the south side (bottom of picture) of the big rock.

 

[Bossroo]

While I don't have solid rock 2 ft down, but I do have hardpan up to 6 inches thick ranging from on the surface to 3- 5 ft. down below the surface. The soil surface has 6 different types of soil from erosion from the nearby mountains. 2 of this eroded soil are hard as a rock when dry, but after a rain the surface is so soft and slippery that when you walk on it you are at risk of slipping and sliding and often falling. So a rock of slab would be problamatic to use as a brace support for an end or gate post. Most people use a " H " brace with the posts 8" -10" diameter and extended down below the hardpan. However, I use 4" diameter galvenized steel posts for an "H" brace extending below the hardpan and set in a 12" to 16" diameter concrete slab.

 

[greybeard]

Yeah I know but since I don't have a jackhammer I had to stop at the ledge 2' down. BTW thanks for the diagram and calculations. Very nice.

BTW, don't know if you saw this on the other thread @greybeard

These are the things that make my fencing job more difficult. Top of that rock is 2' down, I don't even know the extent of it vertically nor to the north (up in the picture) and east. This hole was supposed to be the gate post in the west fence line. The post was supposed to be centered ~ 5" from the top of the picture based on the strike post hole (which was dictated by a rock I hit). I dug the strike post hole first and when I hit this I dug the brace post hole THINKING that it was a rock I could get out. That was when I had a ~10" diameter hole. So I had to dig 3 new holes when I determined there was no way *I* was getting this rock out and dug the 3' hole for the gate post on the south side (bottom of picture) of the big rock.

I would probably have brushed the dirt off the rock good, set the post where it needed to be and poured the concrete in, cementing the post TO the rock in the process--making the post just as immovable as the rock.

 

[Bruce]

I could have but I really don't like the idea of cementing posts in the middle of the field. It would be different if it were a property line fence.

While I don't have solid rock 2 ft down, but I do have hardpan up to 6 inches thick ranging from on the surface to 3- 5 ft. down below the surface. The soil surface has 6 different types of soil from erosion from the nearby mountains. 2 of this eroded soil are hard as a rock when dry, but after a rain the surface is so soft and slippery that when you walk on it you are at risk of slipping and sliding and often falling. So a rock of slab would be problamatic to use as a brace support for an end or gate post. Most people use a " H " brace with the posts 8" -10" diameter and extended down below the hardpan. However, I use 4" diameter galvenized steel posts for an "H" brace extending below the hardpan and set in a 12" to 16" diameter concrete slab.

Well that sounds fun!!! But you can use a power post hole digger or pounder, no?

 

[Bossroo]

I could have but I really don't like the idea of cementing posts in the middle of the field. It would be different if it were a property line fence.



Well that sounds fun!!! But you can use a power post hole digger or pounder, no?

Only the power hole auger. But depending on how deep the wet sediment soil is, the posts would be leaning in short order if they are not cemented in.

 

[CntryBoy777]

Does the strength and support change in any way in relationship to the angle of the corner? Whether obtuse or acute? Is the optimal 90degs?

 

[Bruce]

If you are talking about the angle of the brace wire on an H-brace, I think optimal is 30 degrees at the top, 60 degrees at the bottom. The higher the number of the wire at the top, the more it is not only trying to pull the other post to it but also vertically out of the ground.

JUST A GUESS but I would think you wouldn't want to go any more than 45 degrees. That would make the horizontal and vertical pull equal. Any higher and the vertical pull is greater. However, I don't know how much tension one would have to put on a fence to require enough brace wire tension to actually start to lift the post at various wire angles. I'm sure there are other factors as well, such as how deep the brace post is in the ground.

I used 8' braces because that is how long the posts were They are 3' (mostly) in the ground and the braces are centered at 3.75' because my posts are 5' out of the ground and somewhere I read that the brace should be at 75% of the height of the post.

I found this, might be helpful:
http://www.progressivecattle.com/to...6-4-steps-to-construct-a-long-lasting-h-brace

 

[CntryBoy777]

I was speaking of the angle of the corner being made by the fence itself, or would you have to treat each side separately as a straight line, just connected at the corner to make the turn.