Fence post next to concrete retaining wall


Old 11-10-19, 11:57 PM
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Fence post next to concrete retaining wall

Hi Folks,

This is my first post here. My property is at an elevation of 3 to 4 ft compared to the neighborhood around me and I have a 3 to 4 ft concrete retaining wall all around my property. Wood fence is installed on top of the retaining wall. Now the brackets holding the fence are rusted and couple of brackets are snapped already so my fence is falling apart. How do I fix this? Here is what I am thinking and I need your expert advise here.
Option 1: Install new post brackets by anchoring them on the wall. Since the wall is only 8" wide I am very concerned installing a heavy wood fence. Old brackets are fixed inside the concrete while constructing the wall now I don't have that option.

Option 2: Take a 8ft fence post, dig a post hole (2ft) next to retaining wall and butt the fence post against the retaining wall (meaning the post will be in contact with retaining wall up to 2ft) and pore concrete to fix the fence post next to wall. Here the problem is, fence post once side in contact with the retaining wall and other sides in contact new concrete, Old concrete (retaining wall) and new concrete (pored for fence post) won't bond together. Will this create any problem. I don't have lot of space to move the fence away from retaining wall.

I would really appreciate your suggestions on this.
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Old 11-11-19, 02:57 AM
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How about some pictures of what is there now?
Old 11-11-19, 05:37 AM
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The general rule of thumb for burying a fence post is that 1/3 of the post should be in the ground. To have 8' above ground you should have closer to 30-32" of the post buried in the ground.

I would have to look closely at your retaining wall before installing a fence that tall right against it. Retaining walls face a lot of pressure from the ground. Then you add an 8' sail on top where it has a lot of leverage and it might not end well for the wall.
Old 11-11-19, 01:08 PM
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Thanks for the quick response. I will add the pictures in the evening.
Old 11-11-19, 02:05 PM
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Hi Pilot Dane,

Thanks for your quick response. The retaining wall already taking the load of fence sitting on top of it, so how would it increase the load if we install against it vs on top of it.
Old 11-11-19, 02:05 PM
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I'm assuming a fence based on 4x4 posts.

If I were you:

1) Bolt the new posts to a "post mender" and drive that along the inside of the retaining wall, so that the rest of the post sticks out over the retaining wall.

2) To keep the fence runs from bowing out, I'd run straight steel cables through the tops of the wooden posts. Assuming a rectangular 3 sided back , I'd do three separate runs of cables, drilling . One along each run, drilled through just above the top of the fence sections. Idea is, cables run just above the fence sections so you don't see them. To avoid crossing over at the corner posts, I'd angle the cables that run from the house (perpendicular) down i.e. \, but drill holes for the cables that run parallel up /.

Steel post mender
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Old 11-13-19, 01:36 PM
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Hi Folks,

my apologies for not able to send the pics until now. For some reason I cannot upload the pics I took but found this picture online and able to upload. This is how my fence looks on top of the wall. The plan is to dig post holes on my side of the property flushed to retaining wall and install Postmaster (metal posts) in concrete and do the new fence. But my concern is the metal post if flushed or stood against the retaining wall it will be in contact with new concrete on one side and old concrete with other side. Will that create enough stability to the post or not.

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Old 11-13-19, 04:13 PM
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I am planning to use this as the metal post.

Old 12-08-19, 04:31 AM
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I do not have much experience with use of those specific posts... But, they are steel, they have squared off corners & I am assuming they must have holes in them to drill through the posts into the wood material fencing that you are planning to put up.
I think they are fine....

Your question about one the post and or the cement adhering themselves together. When you dig down below ground it would be a suggestion to remove as much of the soil as possible from the side wall of the retaining wall... clean the area with a water hose if possible. This would allow the new cement to bond to the old cement. The soil itself would act as a barrier and stop the two faces of concrete from joining....
As for one post recently... in regards to putting a load on the wall... If you have a post installed through the wall and the fence is sitting on top of the concrete wall, attached to the posts the weight of the fence is on the posts... and the weight is facing down. If you have a fence on the wall side, and you live in an area that is subjected to high winds, the fence can be blown towards the wall, or away from the wall... If towards the wall I would imagine you would have less issues as the wall would be supporting the fence... But if you do not have your posts down deep enough it is more likely that the fence and their posts will be subjected to eventually rocking back and forth in the ground.. and when that happens it is highly likely that your fence will end up damaging your retaining wall.. Yes,, the fence will become a sail in the wind and there is no stopping the damage unless fixed.

Sinking those posts some 30 inches or more for a 6 foot high fence is best. If you have a 6 foot high fence and wish to attach it to posts cemented in the ground next to a retaining wall I would suggest buying longer posts to satisfy the fencing you have chosen.
Now, please keep in mind what your specific retaining wall is made of... Is it poured concrete or is it cinder block with a mortar face? If it is simply just cinder block I would strongly suggest digging those posts past 3 blocks.. using the depth of the posts as your biggest supporter of the fence... Not the fact that the posts are up against the wall itself.
If the wall is poured concrete & in good shape it might be an option to drill into the wall and use a 2 inch or 2 1/2" steel post... epoxy concrete and just attach the fence to the new posts on top of the wall...
I am not sure that is your best option based on what you said about the original steel brackets being rusted out and snapping off... That description to me sounds like the wall is very old... and it may be a cinder block wall verses a solid concrete wall.
So, going back to installing in the ground... deep as you can, definitely try your best to get the posts cemented up against a clean surface then cement.. Make sure there are no spaces left between the new cement and the old... You would not want water to seep into that space and create a possibility for freezing... that too could easily damage that wall..
Depth , depth , depth ...

Good luck...

Greg's Fence NJ.

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