Everything in a landscape has a purpose, whether it is functional or design-focused. With a little bit of creativity and hard work, you can make a yard fixture serve both purposes. Besides keeping a slope from sliding, retaining walls can be used to add interest and functionality, according to Margie Grace, founder and principal at Grace Design Associates, Inc. based in Santa Barbara, California.
“Retaining walls can be used to sculpt the terrain into interesting shapes or to form terraces which increase the flat space for patio or garden,” she says. “They can serve double duty as a seat wall, a counter or the back wall of a fountain.”
Before choosing a material, Grace recommends that landscapers first assess the situation. Depending on how much soil you need to retain, the load-bearing capacity of your soil, or the depth to the frost line, for example, your material choices could be limited. And different materials vary in look, cost and skill level — so there are many factors to consider as you help your clients choose the right one for their space.
“A homeowner needs to look at technical, aesthetic and cost considerations to decide what to use for wall,” Grace says. “There is no ‘one right choice’ — as many factors, including subjective factors such as personal preference, influence the decision-making process.”
Grace prefers to use materials that have a long life and have little to no impact on the local environment. In her projects she recommends local stone, recycled concrete or plantable sandbags. But she stays away from wood that has been chemically treated because the chemicals can seep into the soil.
Choosing a Design
There are many styles of retaining wall designs, depending on your needs, the amount of earth that needs to be retained and the surrounding landscape. Here are just a few examples:
Block with stucco or plaster: Grace says this type of wall is versatile because you can build it to any height or shape you want, have a variety of colors and textures, and incorporate a variety of design features.
“You can leave openings in the wall and tuck plants or place a fountain into them,” she says. “You can cap it with stone and make it into a sitting wall. You could also paint it if you wanted to.”
Grace says the wall is also structurally sound, but its versatility for design features and structural elements can also make it more expensive to construct. She also points out that although stucco is good for all climates, it must be designed for the on-site environmental conditions such as the freeze-thaw cycle, soil conditions or amount of soil retention.
Mortarless retaining wall system: Grace says this is a rather inexpensive design that usually only requires beginner masonry skills to construct. Because the mortarless design provides a great visual interest through the possibility of added curves and multiple terrace levels, she adds that they’re ideal for yards that are below the wall and for yards above the wall.
“You can really pattern the land and have floating terraces and stairways,” she says.
Stacked-stone walls: As a mortarless, dry stack, this type of design depends on the gravity of the heavy stones. It’s more expensive and requires more labor to lay all the individual stones, but you’ll get a one-of-a-kind wall with more character, Grace says.
“It looks more earthy, and it’s a great way to get more out of your retaining wall than just its ability to hold up dirt,” she says.
Stacked-stone walls can be more expensive, more labor intensive and require a higher skill level.
Requirements of a Retaining Wall
The specific requirements for a retaining wall depend on local zoning requirements. Grace suggests that before starting any retaining wall project, landscapers should check with zoning and building agencies.
Depending on the project’s complexity, you may need a soils report, geologist or an engineer in addition to zoning or building permits. If the homeowner is a part of a home owners’ association, it would be wise to get the association involved as well so it can communicate any guidelines or review procedures.
Vital Addition to Your Landscape
Grace says that a retaining wall can add a great deal of decoration by incorporating design elements like planting spaces or fountains. They can make also make a landscape more user-friendly by offering expanded seating areas, increased privacy and a “layered” view of the surroundings.
“You get to manipulate where the eyes of someone walking around the garden will follow,” she says. “As you lay out walls — forming terraces, steps and paths — you can influence the experience a person has walking through the space.”
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