Adding a seat wall to your landscape can provide extra seating as well as visual appeal. Photo by Mark Storch, Outdoor Architects

What is a seat wall?

A seat wall is a hardscape feature for landscapes that provides both architectural design value and extra seating – as the name implies. This feature is commonly observed as a short wall that is not designed to retain soil, as opposed to a retaining wall and can be integrated in/around gathering areas. The height of the wall is often designed to be at a level that provides comfortable seating for individuals. This fact sheet provides insights that can be applied to designing and building a seat wall on a home property.

How to Build a Seat Wall

Building a seat wall relies on similar practices to other hardscape features (see AgCenter Publication P3867 for reference), wherein an excavated area is filled with aggregate, compacted, and then depending on the design, a sand layer is added on top of the gravel. Finally, the stones for a retaining wall are placed. It is common to see retaining walls installed at the edges of a patio. This allows use of the same materials that are being implemented for the patio base to serve as the seat wall base.

Figure 1. Components of a seat wall.

• Choose Location: The first step is to identify the desired area for a seat wall. Remember, this is intended to be a stand-alone feature and is not designed for holding back soil. That would require more expertise and engineering to do so safely. The purpose of a seat wall is to create a feature designed to support the vertical weight of humans, and not the lateral pressure of soil. As mentioned, it is common to see this built in concert with other hardscape features in the landscape, so it is necessary to bear that in mind when selecting how you design a seat wall and where you install it.
• Excavate: Starting from the ground up, excavate an area wider than the width of the wall. How wide is the seat wall exactly? It depends on the design, the type of stone (including, but not limited to sandstone, bluestone, and other natural stones or materials), and other factors. Regardless of the dimensions, the excavated area must be wider than the width of the wall (which can be as narrow as half a foot to several feet, depending on design). The soil subbase in the excavated area should be compacted to drive out air pockets and to make a more solid ground to work upon.
• Fill: A crushed aggregate (such as #610 gravel, or any type of gravel with fines included) should be added in and compacted to create a solid support base. The depth of that gravel layer should be roughly 4 inches to 6 inches when compacted, depending on the local soil type and other localized considerations.
• Level: Make sure that the compacted gravel base is level. You can refer to AgCenter Publication P3867 for how to set a grade for a gravel base, or you can elect to use a standard bubble level if the width of the gravel base does not necessitate a more intensive grading procedure. While we design patio bases to have a slight grade to channel rainwater away to certain locations, a seat wall may be designed to be level (and is likely best done this way in order to create a comfortable seat). It may be beneficial to use a concrete sand or some other angular sand material to allow fine-tuning of the grade above the gravel. If so, a 1-inch layer would be appropriate.
• Install: With the base at the proper level and height, depending on the design, the stone blocks may be installed. The first row of stone blocks can be laid directly over the base and leveled precisely using a rubber mallet. Each subsequent layer of stones can be laid on top of the previous layer and bonded using masonry adhesives. Make sure that each successive layer does not have four stone corners meeting at any joint to promote stability.

If desired, a capstone that is placed over the final layer of the seat wall can offer enhanced aesthetics and even surface area. Using a capstone that is a different material than the wall can offer a vibrant color and increased interest. Additionally, a wider capstone can create a more table like effect or a more comfortable seat for some people.

Summary

Seat walls provide an architectural element in the landscape with the benefit of being used as a place for guests to rest. Adding a seat wall to the landscape creates a low-profile hardscape feature that can enhance the appeal of a landscape and offer more functional space. Seat walls are not only great for providing a place for people to rest but can be lined with planter boxes or container plants to offer more color. Consider implementing a seat wall in landscapes designed for large gatherings to add more seats or to create a secluded corner of the home landscape without obstructing any views.

For more information on seat walls, please contact your local LSU AgCenter Extension office or visit www.LSUAgCenter.com.