© Elenathewise | iStockphoto

A popular feature to level out backyards, prevent erosion and hold up different structures, retaining walls are meant to last a long time, adding space and visual interest to landscapes.

“Installing new walls can create more usable space in the yard,” says Jake Green, owner of Complete Hardscapes. “A lot of areas that I work in have very steep backyards and are completely unusable. A lot of times, I’m installing a wall so (the customer) can have a swing set, pool or a patio on top of it.”

Green has also installed walls to prevent erosion and as guard walls to keep water away from the house. Some of the walls that Green has installed are 2 to 4 feet tall, what Green calls “sitting wall height.”

Adam Callison, owner of Done Right Landscapes, installs walls for very similar reasons. In addition to creating more usable space in a backyard, he has installed retaining walls as garden features.

“We do what we call guard walls in the front of house, decorative maybe to hold up the front landscape bed,” Callison says.

Callison has also seen people add landscape lighting to highlight walls at night. Normally when it comes to specific features, his clients leave the design up to him. But if clients do have a specific design or feature in mind, Callison follows it to the best of his abilities.

Unlike Green’s business, Done Right Landscapes doesn’t actively market retaining wall repairs, but they get a lot of people calling for repair work anyway.

While retaining walls are meant to last a long time, there are things that can lead to their deterioration over time. A lot of the repair work Callison ends up doing is rebuilding older walls.

“A lot of people used wood walls a long time ago, so it’s a lot of replacement,” Callison says.

Signs and causes.

Older wood tie retaining walls can last up to 30 years depending on the material and installation method. Modern retaining walls can last even longer but can still fail for a few reasons. Most of the time, the signs of wall damage can be seen just by looking at it.

“Cracks on the front, wall’s leaning, roots protruding in the face of the wall – you can pretty much look at a retaining wall and tell if it’s going to fail or not,” says Ryan Endres, owner of Greenscapes Landscaping & Retaining Walls.

Other signs include the wall bowing out or buckling. At that point, it’s imperative to start repairs. But sometimes, people don’t call a professional until the wall has already fallen.

“I did a job in St. Louis by a lake,” Callison says. “His whole wall fell down the hill into the lake.”

For larger walls, there’s a lot of risk involved if it fails. If it’s holding up a heavy structure, that’s at risk of collapsing along with the wall. In that case, there’s damage to property and people involved.

Callison, Endres and Green all say that there’s very little reason for a retaining wall to break down before 10 years. Endres says a retaining wall could last forever if everything was built correctly and if nothing was added to the environment around the retaining walls.

Adam Callison of Done Right Landscapes puts in a lot of retaining walls to hold up front landscape beds, which he calls guard walls.
Photo courtesy of Done Right Landscapes

If a tree was planted too close behind the retaining wall, Endres says that can lead to walls breaking down as it upsets the way the wall was built.

Green adds that building or changing a nearby structure can lead to early deterioration. “Drainage could’ve been diverted to the area, so it’s getting more water than before,” he says. “If they put a swimming pool in their backyard and it was never planned, it could fail if there was a wall there.”

Overall, the deciding factor on whether a wall needs early repair depends on how it was installed in the first place. A lot of repair work on retaining walls can be prevented simply by proper installation.

install and inspect.

Callison says some common mistakes that tend to cause issues in most of the repair jobs he performs include not adding fabric behind the wall or forgetting to add a geogrid. Green says not digging down far enough or forgetting to add gravel can also add to a wall breaking down early.

“The last ones I looked at were between 4 and 6 feet tall,” Green says. “There was no geogrid behind it; there was no gravel behind it at all. It was just compaction and drainage.”

Improper construction can lead to major problems down the line. The gravel keeps hydrostatic pressure off the wall. Geogrid separates the layers of dirt and gravel, and it ties all the gravel to the face of the wall so that it’s one solid structure holding the wall to the hillside.

“Ninety percent of retaining walls are what you don’t see,” Green says. “It’s what’s behind it.”

Whether it’s the fault of an outside element or improper construction, repairing retaining walls can be costly. Endres preaches prevention instead of repair.

“Cracks on the front, wall’s leaning, roots protruding in the face of the wall – you can pretty much look at a retaining wall and tell if it’s going to fail or not.” Ryan Endres, owner of Greenscapes Landscaping & Retaining Walls

“Whoever built your wall needs to come out every year or two to come and inspect the wall to make sure there’s no damages that are starting to occur,” he says.

Some of the things Endres looks for in his inspections are trees growing where they shouldn’t be as well as cracks, erosion and sinkage. He also will look through pipes and make sure they’re not clogged up.

There is an inspection fee attached to this, but he says this is a good way to prevent early breakdown of a retaining wall. Endres also recommends scheduling an inspection after heavy rainstorms to make sure nothing was damaged.

Once a retaining wall is damaged, the process to fix it is difficult and costly. The process of repairing a wall will generally require contractors to tear down the wall and start over again. “By the time the homeowner realizes it needs repaired, it’s too damaged to repair,” Endres says. “Ninety-nine percent of the time, we usually take it down and replace it.”

There are good reasons to tear down a wall and replace it rather than repair it – one being that a contractor can’t tell what’s really causing the wall to break down until they take it apart to see what’s going on behind the wall. By the time the contractor has taken down the wall, fixed whatever’s wrong with it and built it back up, they’ve basically built a new wall.

And that’s why it’s important for contractors to properly install retaining walls the first time around. “If a retaining wall is constructed improperly, you’re going to pay for it twice,” Green says. “It’s going to be about the same cost as the new wall to repair it.”

The author is a summer intern with the GIE Media Horticulture Group.