Is it better to caulk or patch a concrete crack?

For skinny, hairline cracks that aren't getting wider, a flexible polyurethane caulk is best because it moves with the concrete. For wider gaps, chips, or areas where the surface is crumbling, you need a cement-based patch to actually fill the void and rebuild the surface.

How long do DIY concrete repairs last?

If the slab is stable and you did good prep work, a DIY patch can last for years. But if the concrete slab is sinking or shifting, your patch is just a temporary cosmetic fix that will probably crack again within a year. It's masking the symptom, not fixing the disease.

What's the difference between patching and concrete lifting?

Patching is a surface repair, like putting spackle on a hole in the wall. Concrete lifting, also called slab jacking or poly-lifting, is a structural repair where material is injected *under* a sunken slab to lift it back into place and support it. Patching is makeup; lifting is surgery.

Can small cracks lead to major structural problems?

Absolutely. A small crack is an invitation for water to get in. In cold climates, that water freezes and expands, which breaks the concrete and makes the crack bigger. That water can also erode the soil underneath, leading to sinking slabs. Fixing small cracks is the best prevention you can do.

DIY Concrete Patching vs. Professional Repair: A Field Guide (2024)

Quick Answer

Okay, so here's the quick version. If you've got a tiny hairline crack or a small chip in your patio, go ahead and be a weekend warrior. Grab a tube of concrete caulk or a small tub of patch mix for maybe 20-50 bucks. It's an easy fix. But if your sidewalk is sinking, if a crack is big enough to lose a quarter in, or if the whole slab is shifting? That ain't a surface problem. That's a foundation problem. Trying to DIY that is like putting a band-aid on a broken arm. You're just wasting time and money before calling a pro.

DIY Concrete Patching vs. Professional Repair: A Field Guide (2024) visual diagram — Visual guide for diagnosing key fob issues

Common Symptoms

Cracks in concrete surfaces (sidewalks, patios, driveways, garage floors)

Uneven or sunken concrete sections

Potholes or deteriorated patches

Superficial damage (small, hairline cracks)

Spiderweb pattern cracks over a large area (crazing)

A crack that is actively growing wider or longer over time

Possible Causes

Weather fluctuations (freeze-thaw cycles) where water enters a crack, freezes, expands, and breaks the concrete apart.

Poor subgrade preparation during initial installation, leading to uneven settlement and lack of support.

Water infiltration and erosion washing away the soil or gravel base beneath the slab, creating voids.

Overloading the concrete surface with vehicles or objects heavier than it was designed to support.

Ground movement from expansive clay soils swelling and shrinking, or general ground settlement.

Tree root intrusion lifting and cracking the slab from below.

Step-by-Step Diagnosis

Step 1

Assess the size and depth of the damage. Use a credit card to check width; if it's wider than 1/4 inch, it's significant.

Step 2

Determine if the concrete is stable or moving by laying a straight edge across the crack to check for height differences.

Step 3

Tap the surface with a hammer around the problem area and listen for hollow sounds, which indicate a void underneath.

Step 4

Look for the root cause. Check for poor drainage from downspouts, nearby tree roots, or signs of soil erosion next to the slab.

Step 5

Evaluate the surrounding area for other signs of distress, which might point to a larger, systemic problem rather than an isolated crack.

DIY Concrete Patching vs. Professional Repair: A Field Guide (2024) — Key fob troubleshooting and repair overview

DIY vs Professional Costs

Repair Type	DIY Cost	Professional Cost	Time Required
Hairline Crack Patching (DIY)	$10-30	N/A (typically below minimum charge)	Under 1 hour
Small Hole/Spall Repair (DIY)	$25-75	$300-700	1-3 hours
Mudjacking/Slab Jacking	N/A	$700-2,500	2-5 hours
Polyurethane Foam Injection	N/A	$800-4,000+	2-4 hours
Full Slab Replacement	N/A	$3,000-15,000+	2-5 days

Hairline Crack Patching (DIY)

DIY$10-30

ProN/A (typically below minimum charge)

TimeUnder 1 hour

Small Hole/Spall Repair (DIY)

DIY$25-75

Pro$300-700

Time1-3 hours

Mudjacking/Slab Jacking

DIYN/A

Pro$700-2,500

Time2-5 hours

Polyurethane Foam Injection

DIYN/A

Pro$800-4,000+

Time2-4 hours

Full Slab Replacement

DIYN/A

Pro$3,000-15,000+

Time2-5 days

When to Call a Professional Concrete

Any cracks are wider than 1/4 inch or you can see that they are actively growing season over season.
The concrete sections are uneven and have created a trip hazard (typically 1/2 inch difference or more).
You see large, worrisome cracks on a structural element, like your home's foundation wall.
A DIY repair you attempted has failed and the crack has returned, indicating a deeper problem.
The slab is visibly sunken or tilted, especially if it's sloped towards your house's foundation.
You can't figure out the root cause of the damage; a professional can diagnose underlying soil or drainage issues.

Prevention Tips

Ensure all downspouts and sump pump discharge lines extend at least 6-8 feet away from concrete slabs and your foundation.
Grade the soil around your patios and walkways to slope away from the concrete, preventing water from pooling against the edges.
Seal concrete driveways, patios, and sidewalks every 2-4 years with a quality penetrating sealer to protect it from moisture and salt damage.
Address small hairline cracks immediately with a flexible polyurethane sealant to prevent water from entering and causing freeze-thaw damage.
Avoid parking excessively heavy vehicles, like loaded dump trucks or RVs, on a standard residential driveway.

DIY Concrete Patching vs. Professional Repair: A Field Guide (2024) professional repair detail — Professional key fob repair and programming

Frequently Asked Questions

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