April 28, 2017

Can I Build a Fence Above a Retaining Wall?

While the short answer is yes, a fence can be built above a retaining wall; the real question is if the fence is being built above an existing retaining wall or are the wall and fence being constructed at the same time?

If the retaining wall is already built it may be too late to add a fence, or at the very least you may have to give up valuable space behind the wall in order to build it. It is important to know how the retaining wall was built before you proceed with fence construction so the fence installer doesn’t damage the structural integrity of the wall.

If geogrid (mesh reinforcement) was used in the construction of the wall the fence install could tear the grid during construction of the fence which could cause the wall to fail, and if the wall was constructed using No-Fines Concrete the fence installer will not be able to install a fence behind the wall once it has been built.  So don’t wait until the wall is built before you think about the fence!

Here are a few ways to tackle adding a fence above a retaining wall during your retaining wall planning phase:

Place the fence a minimum of 3 ft. (0.9 m) behind the back of the retaining wall.  This method is the preferred because it does not require extra engineering.Construction tubes are placed for the fence posts during the construction of the wall.

A second method is to have the fence directly behind the wall; this method requires a fence above the wall overturning calculation to be completed to understand how the fence interacts with the wall. This calculation is to determine the fence parameters; how deep do the posts need to be placed, how far apart are the posts, how tall is the fence? These factors impact the wall which may cause the top to overturn and fail. To have the fence directly behind the wall you will have to install the construction tubes during the construction of the wall, just like the first method.
Another way to have the fence directly behind the wall is to use a product called Sleeve- It. Sleeve- It is a product that is installed during the wall construction but it does not require extra engineering for overturning.

For more information, check out our tech sheet on Fences above Retaining Walls or visit our website at allanblock.com

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