Concrete Crack Repair: When Cracks in Concrete Mean Trouble

Two Very Different Kinds of Cracks

Not every crack means a sinking slab: hairline cracks that stay level are cosmetic, but a crack where one side sits lower - or that keeps widening - points to settlement underneath. Here's how to tell them apart.

Every concrete driveway, sidewalk, and patio in the Kansas City metro will crack eventually - that's normal for the material. The question isn't whether you have a crack, it's what kind. Hairline cracks that stay the same width and don't change the slab's height are almost always cosmetic, caused by ordinary shrinkage as concrete cures. Cracks tied to settling are a different story: one side of the crack sits lower than the other, the gap keeps widening, or the crack runs along the edge where a slab has visibly dipped. That second kind usually means the soil underneath has shifted or washed away, leaving a void the slab is slowly dropping into. If you're not sure which you're looking at, our why is my concrete sinking guide walks through the warning signs in more detail.

Structural Cracks: Signs of a Real Problem

Settlement cracks look and behave differently. Watch for stair-step cracking near a slab, a crack where you can visibly see or feel one side sitting lower than the other, or a crack that keeps getting wider month over month instead of staying put. Sidewalks and driveway approaches are common spots because they're poured in shorter panels that can settle independently of each other - one panel drops while its neighbor doesn't move at all, and the crack (or the joint) becomes a trip hazard. If a section of walkway has separated enough that you catch your toe on it, that's no longer cosmetic. Our sidewalk and trip hazard repair page covers that specific situation, and if the crack sits over a hollow-sounding spot, it may need void filling before anything else.

Why Kansas City Concrete Cracks and Settles

Most settlement cracks around here trace back to the ground, not the concrete itself. Kansas City sits on expansive clay soil that swells when it's wet and shrinks when it dries out, and our freeze-thaw winters make that cycle worse - the soil is never quite the same volume two seasons in a row. Add a downspout dumping water next to a slab edge, or grading that lets runoff pool against the foundation, and soil gets washed out from underneath the concrete entirely. Once there's a void down there, the slab above it has nothing to rest on, and gravity plus everyday traffic does the rest. None of this is anyone's fault - it's just how clay soil and Midwest weather interact with concrete over years. Fixing the drainage is often part of the real solution, not just the slab.

A Simple Test You Can Do This Weekend

You don't need a contractor to get a first read on a crack. Lay a straightedge or a level across it and see if there's a visible gap on one side - that's height difference, not just a crack. Mark the ends of the crack with a pencil or piece of tape, note the date, and check back in a month; if it's grown past your marks, it's active. A crack that hasn't moved in years and sits flush on both sides is low priority. One that's widening, or where you can feel a lip when you walk across it, deserves a closer look - especially anywhere kids, guests, or older family members walk regularly. Photos over time are the cheapest diagnostic tool you have before calling anyone out.

Concrete Crack Repair: What Actually Fixes a Settlement Crack

For cracks caused by settling, the fix isn't patching the crack itself - it's addressing the void underneath so the slab stops moving. Polyjacking does this with polyurethane foam: we drill a few dime-sized holes near the affected area, inject foam that expands to fill the void, and use that expansion to gently raise the slab back toward level. The foam is waterproof, so it won't break down or wash out the way soil does, and it's light enough that it won't overload the same weak soil that caused the problem to begin with. Cracks that are purely cosmetic don't need any of this - they just need a sealant to keep water out. We check for a height difference before recommending a lift, because raising a slab that doesn't need it isn't a fix, it's an upsell. One honest note on scope: PolyJacks does concrete crack repair by leveling - we lift and stabilize the settled slab so the settlement cracks stop widening. We don't sell standalone crack injection, sealing, or resurfacing; when a crack is purely cosmetic we'll tell you to seal it yourself with a masonry caulk rather than sell you a lift you don't need.

Get an Honest Read on Your Cracks

If you're staring at a crack in your driveway, sidewalk, or patio and can't tell which category it falls into, that's exactly what a free on-site estimate is for. We're a locally owned crew based in Spring Hill, and we walk the whole Kansas City metro on both sides of the state line - Kansas and Missouri - looking at slabs like this every week. We'll check for height difference, look for signs of a void, and tell you plainly whether it's a sealant job, a foam lift, or nothing urgent at all. There's never a charge to find out. Call (913) 713-7794 or fill out our contact form to get a time on the calendar.