If your house is currently tumbling down a slope in a mudslide, your first thought probably isn’t “Hmmm, how much does it cost to build a retaining wall?” - you have more immediate problems.
But to avoid this potential catastrophe, you might want to check into retaining wall costs.
Keep reading for more about retaining wall costs, including:
So, how much do landscapers charge for a retaining wall?
Plan on $80 to $150 per face foot for a cement block retaining wall, says Kim Rubert, landscape designer and estimator at Outback Landscape.
Want a more rustic boulder retaining wall? That’s a bit cheaper, at $50 to $100 per face foot.
Read on to learn more about retaining wall costs.
Made of concrete blocks, boulders or other materials, retaining walls hold the soil behind them back.
That makes them great at preventing harmful erosion that can destroy plants, damage building foundations, and wash away fertilizer and nutrients your soil needs.
A good retaining wall helps prevent erosion by reducing the speed at which water travels across the soil.
So, if you need one, you need one. But they also have many other uses, from cool seating walls to decorative landscape features. More about this in a bit.
First, you need to understand how retaining walls are measured. Unlike calculating the hardscaping costs of a deck or a driveway measured in square feet, retaining walls are measured in “face feet.”
This is the standard method used in construction and engineering when discussing dimensions and the cost of building a retaining wall.
The "face" is the part of the wall that directly faces the soil being held back, so measuring in face feet directly relates to the pressure the wall needs to withstand.
The wall’s length actively holds back the soil pressure rather than the depth or other dimensions.
Engineers and contractors can easily estimate the required materials and structural strength using face feet.
A landscape professional can help you figure out what size retaining wall you need, then calculate the retaining wall cost.
How much do landscapers charge for a retaining wall? Plan on $80 to $150 per face foot for a cement block retaining wall, Rubert says. Want a more rustic boulder retaining wall? She says that will cost $50 to $100 per face foot.
“The application and actual design — and budget, of course — will determine what type of wall the client will use,” she says.
When it comes to the cost to build a retaining wall, smaller retaining walls for seating or landscaping features will be less expensive than larger walls with heavy-duty engineering requirements.
Many factors are involved when it comes to retaining wall prices, from materials to labor to potential engineering costs to the site conditions. And, obviously, the size of the wall. Is it a small garden wall or a massive structure for slope stabilization?
Sure, they often look like simple walls, but there’s more going on than meets the eye.
Retaining walls require precise and skilled planning and construction to withstand the force of the dirt they’re holding back.
You might have read that retaining walls need a licensed engineer to do the plan. Sometimes that’s true, but not usually.
“Most retaining walls that we install will not need engineering,” Rubert says. “But that's not to say the wall isn't constructed well.”
She says that Outback construction crews use Geogrid in retaining wall construction when needed. Geogrid is a synthetic, mesh-like material that reinforces the soil behind a retaining wall. The sturdy material provides additional stability by interlocking with the soil and distributing the pressure more evenly, preventing the wall from shifting or collapsing. It acts as a reinforcement to hold the soil mass together and reduce the pressure on the wall itself.
But if a retaining wall is taller than around 4 feet, an engineered plan might be required, Rubert says, depending on the specific regulations needed in your city or county. If that’s the case, add that fee to your retaining wall cost.
“To get an engineer to design and stamp a plan will cost around $1,500 or more,” Rubert says.
A "stamped” engineered plan refers to a set of construction plans reviewed and approved by a licensed professional engineer, who then places their official stamp on the document. The stamp signifies that the design complies with local building codes and is structurally sound. Some municipalities require this before they issue a building permit.
The cost to build a retaining wall involves more than figuring out the face foot cost:
What’s Your Site Like?
Excavation and grading can be part of the retaining wall construction process. If your property is uneven or inaccessible, the cost to get the area ready for construction can increase.
Drainage Work Adds to the Expense
Drainage is crucial when building a retaining wall, Rubert says, because, without it, water can accumulate behind the wall, creating excessive pressure that can cause the wall to fail by pushing it over.
Proper drainage directs water away from the wall, preventing soil erosion by managing the water flow.
Hardscaping and landscape construction in Boise and Idaho Falls typically uses segmental concrete blocks or natural boulders for retaining walls.
What’s the difference? Take a look:
Segmental Concrete Block
Segmental concrete block retaining walls consist of modular concrete blocks that interlock. You’ll see a solid, vertical front.
They’re super sturdy and can be built tall, if needed, and on steep slopes.
These modular blocks will flex and move as the earth moves, so they won’t crack like a poured concrete wall would.
The blocks are brought to your property on pallets and built by hand.
The blocks come in various colors and textures, so you can match or complement your home or existing landscaping.
As Rubert mentioned earlier, the cost of building a retaining wall is higher using concrete blocks than using boulders.
Natural Boulder Retaining Walls
Here in Idaho, we love rustic landscape design, and a natural boulder retaining wall goes great with that natural look.
Boulders are easy to get here, which makes the retaining wall cost less.
White segmental concrete blocks are placed by hand, and each heavy 3-foot to 4-foot boulder is lifted and set with heavy equipment, like a mini excavator.
That requires extra room on your property for the equipment to maneuver.
A boulder retaining wall takes up more room than a concrete block wall.
“Generally, to do a boulder retaining wall, we’ll need more space because they can't go straight up — they need to take a more tiered approach,” Rubert says.
A 16-foot wall, for instance, can take up 30 to 40 feet on your property.
But boulder walls can’t be built as high as segmental concrete retaining walls, so that’s a consideration if you need a taller wall.
Maybe you’re lucky because you don’t have a worrisome steep slope, tumbling soil or drainage issues.
Go ahead and buy that lottery ticket, but also take a minute to consider that retaining walls do more than you might think. Hardscaping and landscape construction companies in Boise and Idaho Falls can turn retaining walls into all sorts of handy landscaping features:
Love your fire pit? You’ll love it even more with a retaining wall around it that doubles duty as built-in seating, creating a windbreak for your fire.
Make your hot tub area even cozier by adding a retaining wall around it. It will cut the wind on blustery nights and help protect your hot tub from the elements.
Need extra backyard seating? A retaining wall is also perfect built-in seating — and one of the most popular uses for these handy walls around here. Just cap off the walls with flat stones that create perfect sitting places.
Sure, retaining walls are hard-working and practical, but they can also create landscaping magic. Skilled designers and builders can create unique landscaping features by adding focal points, carving out charming garden rooms, and transforming pesky slopes into elegant multi-level terraces.
Let’s make this easy: no.
Maybe you’re balking at the cost of building a retaining wall and consider yourself pretty handy. Before you set aside Saturday afternoon to DIY a retaining wall, know that retaining walls are trickier than they look. They take lots of precise planning and calculation to work properly. It’s not just about stacking concrete blocks.
Soil is heavy, especially when saturated with rain. Your retaining wall has to support literal tons of soil pressure. A poorly constructed retaining wall can suddenly break, causing a landslide of dirt.
And proper drainage is crucial, remember? Water pressure building up behind the wall can compromise its stability.
Do you know how to design an effective drainage system? Professionals do.
Leave this job to experts so your wall doesn’t bulge, collapse, or pose a real danger on your property.
If your DIY retaining wall fails, and you have to pay a professional to re-do it, you’ve paid double.
Whether you have an erosion problem out back or you could use an extra seating wall for all those cookouts you host, a retaining wall can come in handy.
We’d love to help.
Outback Landscape is a full-service company offering hardscaping and landscape construction in Boise and Idaho Falls.
We install beautiful, functional landscapes and stay with you for the long haul, taking care of your property through all four seasons.
We serve residential and commercial properties in Idaho Falls, Rexburg and Pocatello, Idaho, and Bonneville, Madison and Bannock counties. Call us at 208-656-3220 or fill out the contact form to schedule a no-obligation meeting with one of our team members. We can’t wait to hear from you.