What We Know About Retaining Walls (From Years of Doing Them Right)

When it comes to retaining walls, there’s a right way to build them—and then there’s the fast way (which usually doesn’t end well). As a landscaping company that’s built our fair share of these, we wanted to share some real-world knowledge about what makes a retaining wall last. Whether you’re thinking of DIYing a small one or hiring a contractor, here’s what we know works.

It All Starts with the Base

We can’t stress this enough: the base is everything. If it’s not right, your wall won’t stay right. The most common reason walls fail? Poor base prep.

We recommend roughly 1 inch of compacted gravel base for every 8 inches of wall height, but honestly—going deeper is better. For example, a 4-foot wall should start on at least 6 inches of compacted angular gravel. That’s your foundation.

Pro Tip from Our Crews: Knock Off the Lip

If your block has a rear lip, it can make the first row sit uneven on gravel. We often knock off the lip on the base layer with a sledgehammer so the first course can sit perfectly flat and level. It’s a simple trick that helps keep the entire wall straight from the ground up.

Use the Right Rock for Backfill

A common mistake we see is the wrong kind of backfill. You need crushed, angular rock—not pea gravel, not smooth river stone. Crushed rock compacts better and locks together, which means better support and less shifting. Plus, it allows water to drain through instead of building up behind the wall.

At least a foot of that crushed rock should go behind the wall, and if you want to go the extra mile, add landscape fabric between the rock and soil to prevent clogging.

Drainage Makes or Breaks It

One thing we always plan for is drainage. Water is heavy, and when it gets trapped behind a wall, it builds pressure—and that pressure can eventually knock your wall over. Every wall we build includes drainage stone, a perforated drain pipe along the base, and an outlet or weep holes to let the water escape.

It’s not optional—it’s part of what keeps the wall standing.

Build with a Setback

Another key element we include in almost every wall is a setback. That means the wall leans slightly backward—usually at a 6–12 degree angle. Most block systems are designed to help you achieve this automatically, but it’s something we always double-check.

That small tilt helps the wall handle pressure from behind and keeps everything locked in tight over the long haul. It’s just one more way we build structural integrity right into the wall.

Watch for Movement—That’s a Red Flag

If a wall is shifting, blocks are cracking, or the soil behind it is sinking, that’s a warning sign. Things moving around your retaining wall is never a good thing. A well-built wall should sit tight and solid for years. If it’s not, something’s off—usually the base or drainage.

Bigger Walls Need Bigger Plans

We see this one a lot: walls over 2 feet tall built on barely any base. That’s a recipe for failure. The taller the wall, the deeper the base and the stronger the structure needs to be.

If someone’s building a 4- to 6-foot wall with only 1–2 inches of gravel underneath? You need to find someone else. That wall won’t hold up.

Materials Cost Money—And That’s Normal

Let’s be real—retaining wall materials are expensive. Concrete blocks, compacting gravel, pipe, fabric—it adds up fast. That’s why it’s totally normal for us (or any contractor) to ask for a materials deposit upfront. It’s not a scam—it’s just how we get quality materials on site before the work starts.