Concrete cracks no matter how great a job your contractor did. While there’s no match when it comes to concrete’s surface durability, it is susceptible to damages that come with annual freeze/thaw cycles. Some concrete cracks are nothing to worry about, but others can lead to thousands of dollars of damage to your home. Find out how concrete cracks happen and which ones you need to worry about and get fixed now.
What Is Concrete?
Concrete is a common building material made up of cement, sand, gravel and water. When these materials are mixed together, the water eventually evaporates and the remaining ingredients cure into a hard, solid slab of concrete. Concrete is most typically used in homes for foundations and ground-level floors, although more recently it’s come into fashion for countertops and accents. We’ll be focusing on foundational cracks as these are the most expensive and important to fix.
Why Does Concrete Crack?
The concrete in your foundation is exposed all year long to various forms of weather and is susceptible to freeze/thaw cycles. Just like your doors contract and expand throughout the year, so does your concrete. Concrete has very strong compressive strength (force that pushes something together) but poor tensile strength (force that pulls something apart). Below are the most common factors that lead to concrete cracks.
Drying Shrinkage
This is one of the most common reasons for concrete cracks. During the curing process, there is a chemical reaction between the water and cement. The cement particles will begin to dry out and this will cause hairline cracks to appear.
Thermal Shrinkage
As the temperature changes, all materials contract and expand to an extent. When concrete begins to cool down, it shrinks. This typically happens after the curing phase and can also result in hairline cracks.
Settlement
The ground around your foundation will naturally settle. The trouble comes when it settles significantly. This can cause the concrete to crack and cause significant damage under the right circumstances.
Corrosion
To help with the poor tensile strength of concrete, steel reinforcing is often used. This is called rebar. Sometimes the steel rebar corrodes inside of the concrete which causes it to expand and crack.
Concrete Cracks To Worry About
All concrete will eventually crack and not all cracks should set off alarm bells. Due to the fact cracks are common, it’s important that you’re able to distinguish when a crack is bad enough that you need to hire a professional concrete contractor to fix it.
One easy way to determine the severity of a crack is to measure it. Experts find that cracks under ⅛ inch wide can be left alone and do not require immediate action. Cracks between ⅛ and ¼ inch wide may need to be checked out by a pro. In this case, you want to look at the concrete on either side of the crack. Has it significantly shifted? Can you see where the two pieces have moved into different directions? This could be a sign of settlement and a potential problem. If you’re concerned, it’s best to have a concrete pro take a look.
If you discover a crack that is larger than ¼ inch wide, you need to contact a pro asap. Cracks that wide indicate that there has been significant movement within the foundation and you could have a serious problem on your hands. To ensure the crack and the problem do not become bigger, connect with a local concrete pro to assess the situation.
Larger stress cracks will appear in your foundation when your house or the ground under it shifts. While these stress cracks usually do not threaten the structural integrity of your house, they do create an entry point for insects and pests, groundwater, and radon gas. If you notice large cracks or bulging walls, contact a structural engineer for a deeper analysis.
Cracks are inevitable to all forms of concrete. If you notice a significant crack in a surface that was recently poured, there’s a good chance the mix was of inferior quality or proper installation techniques weren’t followed. If this is the case, you need to ask your concrete contractor about a replacement. Check your contract for a warranty to see if the damage is covered.
Fix Concrete Cracks Now
If you’re concerned about cracks in your concrete, now is the perfect time to connect with a pro and get them fixed. Fall is the perfect time to seal concrete cracks because of the moderate temperatures. During the winter, the cold temperatures cause cracks to open to their widest. In summer, the heat causes the cracks to contract. During the fall, cracks are open midway, making them easier to see and fill properly.
Spring can also be a good time to seal your concrete cracks, but you must ensure work is done in dry conditions. The same can be said for fall, only have the work done if it is in dry conditions. If there is any moisture present, it will decrease the effectiveness of the seal, or worse, create frost action in the winter which will render the seal ineffective.
When you’re ready to get your cracks fixed, or if you just need some advice about the state of your concrete, click here to connect with a concrete pro. Your pro will be able to tell you how severe your cracks are and the best possible solution to fix them. Remember that cracks in concrete are inevitable, but you need to fix them to maintain the structural integrity of your home.
Article updated June 2022.
