Understanding Concrete Cracking: Causes, Concerns and Solutions

Concrete Cracking: How to Identify and Fix Foundation, Basement & Wall Cracks

Although concrete cracking is common, it is important to differentiate between minor, cosmetic cracks and those that suggest deeper structural problems if you notice cracks in your home’s concrete foundation, basement floor or walls. Read on to learn how to identify the signs of serious issues and the best ways to address them.

We’ll cover the following topics in this article

1. Why Does Concrete Crack? Understanding the Causes
2. Types of Concrete Cracks: What You Need to Know
3. Cracks in Basement Floors: When to Worry
4. Cracks in Concrete Walls: Causes and Concerns
5. Repair Solutions: Fixing Cracked Concrete
6. Concerned About Concrete Cracks? Get Professional Help Today!
7. Frequently Asked Questions About Cracks In Concrete

Why Does Concrete Crack? Understanding the Causes

Concrete cracking is a common issue that can occur in both new and old properties. It happens when the concrete expands, contracts or experiences stress beyond its capacity, causing visible fissures. While some cracks are purely cosmetic and do not affect the integrity of the structure, others can signal serious underlying problems. Here are the main causes of concrete cracking:

Natural Causes:

Shrinkage as Concrete Cures: When concrete is poured, it naturally shrinks as it dries and cures. This shrinkage can lead to small, hairline cracks.

Temperature Fluctuations: Concrete expands and contracts with temperature changes, and excessive fluctuations can cause cracks to form.

Foundation Settlement: Over time, the foundation of a building may settle as the ground beneath it compresses, causing cracks to appear in the concrete structure.

External Factors:

Moisture Changes: The presence of moisture can cause concrete to expand when wet and shrink when it dries, which can lead to cracking, especially if the concrete is not properly sealed.

Heavy Loads or Vibrations: Large loads on the concrete surface or vibrations from nearby construction can weaken the concrete and create cracks.

Internal Factors:

Poor Concrete Mix or Improper Curing: If the concrete mix contains incorrect proportions or is not properly cured, it may be more prone to cracking.

Contaminants: The presence of chemicals or air pockets within the concrete mix can also contribute to weakness, making cracks more likely.

Types of Concrete Cracks: What You Need to Know

Understanding the different types of concrete cracks can help you determine whether the cracks in your home are a cause for concern.

Hairline and Shrinkage Cracks: These fine cracks often result from shrinkage as the concrete cures. While typically not a major concern, they should be monitored.
If hairline or shrinkage cracks widen, deepen or allow water to seep through, it’s a sign that further inspection is necessary to prevent long-term damage.

Structural Cracks: These are larger and more serious cracks caused by factors such as foundation settlement, heavy loads or inadequate reinforcement.

Structural cracks can weaken the strength of your foundation, floors or walls. Signs of structural cracks include uneven surfaces, shifting or water leakage.

Settlement Cracks: These cracks occur when the ground beneath the concrete shifts or settles, often due to soil moisture changes or natural foundation settling. Minor settlement cracks may not pose immediate risks, but severe cracks that cause noticeable shifts in the foundation or walls may signal underlying structural issues.

Cracks in Basement Floors: When to Worry

Basement floor cracks are common, but knowing when to worry can save property owners from costly repairs and hazards. These cracks often result from natural shrinkage as the concrete cures. However, some cracks signal more severe issues that need immediate attention.

Size: If a crack is wider than 3mm, it may indicate structural problems. Wider cracks can allow water seepage, leading to moisture issues and potential mould growth, which can harm both the building's integrity and indoor air quality.

Location: Cracks running along the walls or those that disrupt the floor's continuity might suggest foundational movement. This can compromise the stability of the entire structure, warranting immediate evaluation by a structural professional.

Progression: Cracks that continue to lengthen or widen over time are a red flag. Monitoring their progression can reveal patterns that point to underlying issues like soil settling or expansive soil conditions.

Frequency: Numerous cracks appearing simultaneously or within a short period might hint at a deeper foundation problem. Such occurrences should not be overlooked, as they may require substantial repair work.

Recognising these red flags early helps maintain your property's value and ensures a safe living environment.

Cracks in Concrete Walls: Causes and Concerns

Concrete wall cracks can develop due to settlement, which occurs when the ground beneath a building shifts or subsides, leading to structural movement. This is a common issue in areas with highly compressible soils or improper compaction before construction.

Thermal expansion is another cause; as concrete contracts and expands with temperature changes, tension cracks may form along the walls. Additionally, structural load, particularly if the concrete wall bears significant weight without adequate reinforcement, can lead to cracking.

Repair Solutions: Fixing Cracked Concrete

Addressing cracks in concrete surfaces requires the right repair techniques to ensure durability and prevent further damage. Below are common repair methods and insights into why seeking professional assistance is often necessary for more severe issues.

Epoxy Injection: Used for sealing cracks in concrete walls and structural elements, epoxy injection restores structural stability by bonding cracked surfaces. It is particularly useful for narrow cracks.

Slab Jacking: This method involves lifting and stabilising sunken concrete slabs by pumping a grout mixture beneath them. It is ideal for addressing settlement issues in driveways or pavements.

Sealing: Sealing surface cracks with a flexible sealant prevents water penetration and further deterioration. This method is suitable for non-structural cracking on driveways or footpaths.

Resurfacing: Applying a concrete overlay can refresh and smooth out cracked surfaces, offering a cost-effective, visually appealing solution for superficial cracking.

For severe or complicated concrete issues, consulting a professional is crucial. Professionals will assess the extent of the damage, identify the underlying causes and recommend appropriate repair strategies tailored to your specific needs. This ensures a long-lasting solution and prevents recurring problems.

Concerned About Concrete Cracks? Get Professional Help Today!

Concrete cracking can lead to serious structural issues if left unaddressed. Whether you're concerned about cracks in your basement floor or have noticed a concerning crack in a concrete wall, understanding the underlying cause is crucial. Don't wait until minor cracks turn into major problems; find peace of mind by connecting with available tradespeople through MyBuilder.

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Frequently Asked Questions About Cracks In Concrete

Is it possible to prevent cracks in concrete?

While some cracking is inevitable, it can be minimised by using the correct concrete mix, proper curing techniques, adequate reinforcement, and ensuring proper drainage and grading around the foundation.

Should I repair concrete cracks myself or hire a professional?

Hairline or superficial cracks can often be repaired using DIY products. However, structural cracks or those causing significant issues should be evaluated and repaired by professionals to ensure safety and longevity.

How long does it take for concrete to crack after being poured?

Concrete can begin to show signs of cracking within days or weeks, particularly if it was not properly cured or if environmental factors, such as temperature fluctuations or moisture changes, are present. Shrinkage cracks can occur shortly after pouring, while larger, more serious cracks related to foundation movement may take longer to develop.

How can I prevent cracks from forming in my driveway?

To prevent cracks in your driveway, ensure that it is properly constructed using the right mix of concrete and reinforced with steel rebar or wire mesh. Proper drainage around the driveway is also essential to prevent water from pooling and causing shifts in the concrete. Sealing your driveway every few years can also protect it from moisture and temperature changes.

What is the best way to reinforce concrete to prevent cracking?

Reinforcing concrete with steel rebar, wire mesh or carbon fibre strips can help prevent cracking by providing additional strength and support. These reinforcements help the concrete handle external pressures, such as weight or soil movement, and distribute stress more evenly. Proper curing and a good concrete mix are also essential to prevent cracks from forming.