Retaining Wall and Fencing

by Dave G.
(Washington, DC)

I've got a rather unattractive slightly sloped retaining wall up against one side of my back yard. We are on the low side of the wall. The previous owners of the house attempted to fence in the backyard. They basically installed the fence right in front of the wall (basically flush with the base of the wall).

The problem is the fence was poorly built and is falling apart. It also seems that water drainage off the retaining wall has washed away much of the ground at the base of the wall and has weakened the foundation for the fence. I don't believe the posts were anchored properly in the first place. It has basically fallen and is now just leaning up against the wall.

It is my intention to tear down the entire fence and build up a new one. My concern is how can I properly anchor the posts at the bottom of this wall without having to worry about water drainage washing away the foundation? Even if I set them in concrete, the dirt around them could be washed away leading to the same situation.

On that note I do feel that having a fence against the wall is unsightly. Setting the fence away from the wall a few feet could solve the problem but would effectively cut down on the size of my back yard. It's a very small area in the first place.

I thought of possibly not fencing that one side of the yard and trying to incorporate the retaining wall into my landscaping but as I said it is very unattractive. I also would not be able to attach my fence to the wall since the high side and area surrounding it is "community property". This would leave a space between my fence and the wall that any kid who is feeling adventurous could climb between and get into our yard. Obviously some creative planning is needed here and I could use all the help I can get.

Hi Dave,

From your description, I believe I understand the
positioning of the fence and the wall and your problems.

My first question would be, are you considering putting up a new fence to hide the wall or because you actually want the fencing for privacy and/or enclosure?

If you want a fence just to hide the wall, you can hide any wall with plantings so that you never even see it. The plants you would use would depend on how high the wall is, what the sun conditions are, if you have a deer problem, etc.

If you want to give me that information, I could give you some suggestions.

Installing a new fence is another matter (if you actually want the fence). The drainage problem might be caused by a few different things. It might be that the land is totally flat and the water has nowhere to go. It also might be that the land on the high side of the wall is very steep and causing a large amount of water to seep into the wall.

Drainage problems can be rectified, depending on what the situation is. For example, if the land is flat and the water is not draining anywhere, you might be able to re-grade it so that the water flows away. If there is a huge amount of water coming from the top of the wall, drains at the top of the wall (if this is your property or you could get permission) might be the answer.

Another solution to the water compromising the fencing is to install perforated pipe at the bottom of the wall, pitch it lengthwise, and lead it to another area. This method would bring the water away and alleviate the problem of sitting water. Your existing conditions would have to be known before an accurate solution could be suggested.

One other thing I'll mention is the make up of your soil where the fence is. Sandy soil will make the water seep into the ground more easily than if you have a clay-like soil.

Please let me know if you need more input.


Comments for Retaining Wall and Fencing

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Drainage Pipe
by: Susan

Hi Dave,
I'm glad I could be of help!

If you wind up using the PVC piping, you'll want to wrap it in filter fabric to prevent anything getting through the holes, other than the water. Also, cover it with decorative stone, which will help the water get into it from the top surface.

You can lead it away, and the connect the PVC pipe to solid pipe if you need other words if it has to continue beneath lawn.

You can also plant trees for privacy and to block the wall. There are narrow evergreens that would probably work. Some evergreens have a "fastigiata" variety, which means they are a more narrow kind. I suggest this as they get tall and I also know you don't have a lot of space.

Good luck.

by: Dave G.

Hey Susan,
Thanks for the response. Yes the fence is primarily for privacy. We also have a dog so having the backyard completely closed off is a must. THe wall has to be a good 15 feet high. There's a parking lot on the high side so folks are always looking down directly into the yard. I'll address that later. Maybe some plantings in and around the fence, even behind it, sound like a very good idea to take the emphasis away from that wall. Did I mention how unsigltly it is? At least we don't have a deer problem. The land is not flat at all so that water is coming from somewhere. I did some research of perforated pipe to alleviate the drainage issue and it seems a french drain could in fact solve my problem. A nice creative solution. Thanks a bunch. Now just to figure out how to make it work for me.

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