5 Common Issues That Cause a Retaining Wall Near Tacoma to Fail (And How to Prevent Them)
1. Why Homeowners Near Tacoma Worry About Retaining Walls
If you’re reading this, chances are you’ve either noticed cracks in your retaining wall, some strange bulging, or maybe the ground behind it just doesn’t look quite right anymore. You might be thinking, “Is this going to collapse? How much will it cost to fix? Could it damage my yard or home?” These are real concerns—and you’re not alone.
We’ve talked with homeowners all across Thurston, Pierce, Kitsap, and Lewis Counties who’ve had the same gut-wrenching worries. Most of the time, they were just trying to keep their yard from sliding or support a slope with something solid. But when retaining walls start to fail, things can get expensive—fast.
At Southbay Septic & Excavation, we’ve seen what works and what falls apart. This guide is here to explain the most common reasons retaining walls fail near Tacoma—and how to stop those problems before they start.
2. Failure #1: Poor Drainage Behind the Wall
This is the big one.
The ground in the Tacoma area sees a lot of rain, especially in fall and winter. When water gets trapped behind your retaining wall with no way out, pressure builds up—fast. We call it "hydrostatic pressure," and it’s one of the most common reasons walls start to bow, lean, or crack wide open.
How it shows up:
Water stains or wet spots behind the wall
Cracking or bulging in the middle
Leaning outward, especially after heavy rain
How to prevent it:
Install proper drainage: think drain pipes (weeping tiles), gravel backfill, and weep holes.
Make sure the soil behind the wall is not dense clay—it holds too much water.
Consider French drains if water is pooling nearby.
Even the strongest wall will fail if water is pushing against it with nowhere to go.
3. Failure #2: Using the Wrong Materials for the Job
Just because something looks strong doesn't mean it’s made for the job. We’ve seen people try to hold back entire hillsides with loosely stacked stones, railroad ties, or thin concrete blocks from the hardware store.
What goes wrong:
Timber rots over time, especially with all the moisture we get here.
Cheap concrete blocks crack when pressure builds.
Rebar or connectors rust or break if they’re not the right type or installed properly.
How to do it right:
Use engineered blocks, poured concrete with reinforcement, or properly treated retaining timbers.
Make sure materials are rated for structural loads, not just decorative edging.
We always tell homeowners: if the wall is taller than 3 feet or holding back a slope, don’t DIY it with leftover materials.
4. Failure #3: Lack of Proper Footing and Support
Retaining walls are more than just stacked blocks—they’re part of the earth-moving system holding your yard in place. Without a strong footing and proper support, your wall might not survive the next storm—or the next few years.
Common signs of footing issues:
The wall is sinking on one side
There are gaps at the bottom
Sections are sliding forward
Here’s what a good footing should include:
A compacted gravel base to spread the weight evenly
Enough depth to avoid frost heave (especially important in colder inland parts of Pierce or Lewis Counties)
Geo-grid or tiebacks for taller walls to connect the wall to the soil it’s holding
We’ve seen small walls survive decades and big ones collapse in a year—all because of the footing.
5. Failure #4: Soil Pressure That Wasn’t Planned For
Dirt is heavy. Wet dirt is even heavier. Now throw in a slope, tree roots, and maybe a parked car above it—suddenly, that wall has to act like a small dam. If it wasn’t built to handle that kind of pressure, something’s going to give.
What causes excess soil pressure:
Slopes steeper than they appear
Added weight above the wall (like patios, sheds, or even kids' playsets)
Poor compaction when the wall was first built
How we fix or avoid it:
Calculate expected pressure before building (yes, there’s math involved)
Use tiebacks, anchors, or thicker materials when pressure is high
Add terracing to split large slopes into smaller, manageable levels
Most people don’t think about the weight behind the wall—until it starts to crack.
6. Failure #5: Poor Workmanship or DIY Mistakes
Let’s be honest: sometimes the wall fails because it was never built right in the first place. Maybe it looked fine when it was finished, but without the right prep work underneath or solid reinforcement, it wasn’t going to last.
What this usually looks like:
Crooked or uneven walls
Mortar crumbling or gaps between blocks
Walls that move when pushed
We’ve fixed a lot of DIY retaining walls—and it’s usually more expensive to fix than to build it right from the start.
Tips if you’re going the DIY route:
Watch videos from licensed pros, not just hobbyists.
Check local codes—some walls need permits or engineering.
Don’t skip the base. That’s where most mistakes begin.
A retaining wall isn’t just a weekend project—it’s part of your home’s foundation system.
7. How to Keep Your Retaining Wall Standing for the Long Haul
If your wall’s already showing signs of failure—or you’re planning a new one—here’s how to make sure it lasts:
Do the groundwork (literally):
Make sure your wall has a compacted gravel base and good drainage.
Pick materials that match your soil and slope:
Some yards need reinforced concrete, others are fine with timber or modular block.
Think about the water flow:
Watch where water naturally drains, and plan to route it away from the wall.
8. When to Call in a Retaining Wall Expert in Tacoma
Here’s when it’s time to bring in a pro like us at Southbay Septic & Excavation:
Your wall is leaning, cracking, or pulling away from the ground
You need a new wall over 3–4 feet high
The wall will hold up a driveway, building, or slope above
You’re just not sure what’s going on, and need a second opinion
We’ve worked on walls across Tacoma, Olympia, and beyond. Whether it's fixing a bowed concrete wall or designing something from scratch, we’re here to help you avoid future headaches—and future repair bills.
9. Closing Thoughts: Avoiding Stress with the Right Help
Retaining walls aren’t something you should have to think about every time it rains or freezes. They’re supposed to give you peace of mind, not problems.
If you’re near Tacoma and worried about a retaining wall—or just want to make sure your next one is built to last—Southbay Septic & Excavation is here to talk, walk your property, and help you come up with a solution that actually works. Not some cookie-cutter fix. Just something solid that holds up year after year.
We don’t believe in rushing things or selling you more than you need. We’re here to help you get it right.
