What to Do When Your Concrete Starts to Give In

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You know that moment when you step onto your driveway or patio and feel it dip just slightly under your weight? Or maybe you’ve noticed cracks forming where they never existed before. These small signs often get brushed off as harmless wear and tear. But in truth, they’re concrete red flags.

When your concrete starts to give in sink, crack, or crumble it’s telling you something. And the sooner you listen, the better the outcome.

Why Concrete Fails: A Quick Breakdown

Concrete seems solid, unshakable, even permanent. But like any other material, it’s vulnerable to time, environment, and what lies beneath. Let’s explore some of the reasons your concrete might be starting to fail:

1. Soil Movement and Erosion

Beneath every slab of concrete is soil and soil can shift. Heavy rain, poor drainage, or improper site preparation can wash away or compress the earth under your concrete, causing it to lose support. Eventually, the concrete begins to sink or crack under pressure.

2. Freeze-Thaw Cycles

If you’ve lived through a St. Louis winter, you know how unpredictable the weather can be. When moisture seeps into small cracks and freezes, it expands. This freeze-thaw cycle causes the concrete to stretch, split, and weaken over time.

3. Tree Roots

Roots from nearby trees or bushes don’t just grow down they grow outward, often right under your sidewalks or driveways. As they push upward or decompose, they cause lifting or voids under the slab, resulting in cracking and shifting.

4. Poor Installation

Sometimes, the problem starts from day one. If your concrete was poured on loose or uncompacted soil, it may not have had the foundation it needed to stay in place. Combine that with time, moisture, and weight, and the slab begins to fail.

 

Warning Signs You Shouldn’t Ignore

Not sure if it’s time to call in a professional? Here are a few signs your concrete is crying for help:

  • Cracks that widen over time

  • Sections of your walkway or driveway that sink or tilt

  • Water pooling around the slab

  • Gaps between your concrete and surrounding structures

  • Uneven steps or shifting patio slabs

These signs may seem like small inconveniences now, but they often lead to bigger and more expensive repairs later.

The Modern Fixes That Work

You don’t have to live with uneven or damaged concrete. Thanks to advances in technology, there are fast, clean, and cost-effective ways to restore your surfaces without ripping everything out.

1. Polyurethane Foam Injection 

This method is like giving your concrete a lift from below. A lightweight polyurethane foam is injected into the voids underneath the slab. As it expands, it raises and levels the concrete back to its original position.

Why it’s popular:

  • Minimally invasive

  • Fast cure time (ready in hours)

  • Long-lasting and waterproof

  • No heavy machinery or big mess

It’s ideal for driveways, patios, sidewalks, garage floors even pool decks.

2. Traditional Mudjacking

This older method uses a slurry of cement and soil pumped under the slab to lift it. While it can work for certain large applications, it’s heavier and messier. Plus, it doesn’t hold up as well against moisture over time.

Mudjacking might still be used for industrial or legacy structures, but for residential fixes, polyurethane has become the go-to.

3. Slab Replacement

Sometimes the damage is too extensive to fix with lifting. If your concrete is crumbling or severely cracked, replacement may be the safest route. It’s more expensive and requires demolition and repouring, but it’s necessary in extreme cases.

Real-Life Fix: A Patio Saved in One Afternoon

Take this recent case in a Chesterfield backyard. The homeowner noticed her back patio slanting toward the house and water pooling after every storm. The concrete looked intact, but it had clearly settled unevenly.

A quick inspection revealed the problem: soil erosion had created gaps under the slab. Using polyurethane injection, the contractor lifted the patio back into place within just two hours. No need for demolition, no muddy mess, and the water now flows away from the home, as it should.

What Happens If You Wait?

Let’s say you notice the cracks, the slanting, maybe even a little water collecting near your foundation. But you decide to wait it out.

Here’s what that delay can cost:

  • Trip hazards and liability: Uneven concrete isn’t just inconvenient; it’s dangerous. One bad fall could become a legal issue.

  • Water damage: Poor drainage can lead to foundation problems, basement leaks, and mold growth.

  • Decreased property value: Visible damage affects curb appeal and appraisals.

  • Bigger repair bills: The longer you wait, the worse the damage gets. What could’ve been a simple lift might become a full replacement.

 

Conclusion: Take the First Step Toward Solid Ground

Whether it’s your driveway, patio, or walkway, cracked or sinking concrete doesn’t fix itself. The good news? Most of the time, it doesn’t have to be a big ordeal.

Today’s repair solutions are cleaner, faster, and more affordable than ever. All it takes is a free inspection to get started.

If you’re looking for reliable, long-lasting concrete repair in St. Louis, STL Polyjack has you covered.