When Fences are Needed Above a Retaining Wall

When Fences are Needed Above a Retaining Wall

If your next client is requesting a fence or railing above a retaining wall and you are not sure what to do, have no fear, we have the information to help you! The implementation of a fence or railing above a wall should be considered before the retaining wall has been built and needs to be included in the design of the wall.

Fence posts require concrete forms to be placed within the reinforced zone of the wall. If the retaining wall has already been built you may be required to re-excavate the site to install the concrete forms for the posts, this increases time and money spent on the project. Rather than re-excavating you may choose to use an auger to place the forms. Inevitably, using an auger will result in damage to the geogrid, weakening the reinforced mass. The ideal construction process for a wall with a fence above is to place the concrete forms during the construction of the retaining wall.

The first consideration when designing an above wall fence is the post footing location. The preferred location for a fence footing is a minimum of 3 ft (0.9m) behind the back of the wall. This configuration utilizes the soil mass between the wall and the footing to reduce the overturning forces provided by the fence.

If your application requires the fence to be installed closer than 3 ft (0.9 m) or directly behind the wall, a simple solution would be to use Sleeve-It. If you are not going to use Sleeve-It you will need to consider the additional overturning load acting at the top of the wall. Our Top of Wall Fence Overturning Sheet provides information on how to address this case. In any case, no matter the location of the footing a local engineer should be consulted before building your wall.