If your home has a concrete foundation, there’s a good chance you’ll deal with cracks at some point. While the normal settling of the house often causes these cracks, they can also indicate bigger problems. Left unchecked, cracks in your foundation can lead to water damage, mold, and even structural instability.
The good news is that you can repair most cracks in concrete foundations relatively easily and cheaply. In this article, we’ll show you how to identify and fix common types of cracks in concrete foundation walls.
Types of Cracks in Concrete Foundation Walls
There are several different types of cracks that can occur in concrete foundation walls. The type of crack will determine the best method for repair. Here are some of the most common types of cracks:
Hairline cracks are the most common type of cracks in concrete foundations. These cracks are typically very thin (1/16 inch or less) and don’t pose a structural threat to your home. Hairline cracks are often caused by normal expansion and contraction of the concrete as it cures.
Horizontal cracks are another common type of crack in concrete foundation walls. These are wider than hairline cracks (1/4 inch or more) and can run for several feet along the wall. Horizontal cracks are often caused by the settling of the foundation or poor construction techniques.
Vertical cracks are usually narrower than horizontal cracks (1/4 inch or less). They can run the entire height of the foundation wall or be confined to a small section. Vertical cracks are usually caused by hydrostatic pressure, which is created when water builds up in the soil around your foundation.
Stair-step cracks are horizontal or vertical cracks forming along concrete joints. Joints are placed in concrete during construction to control cracking. Stair-step cracks form when the joint sealant fails, allowing water to seep into the crack and cause it to widen.
Diagonal cracks can run in any direction but typically form at a 45-degree angle from either corner of the foundation wall. Diagonal cracks are often caused by unequal settling of the foundation or poor construction techniques.
Repairing Cracks in Concrete Foundation Walls
Once you’ve identified the type of crack in your foundation wall, you can select the best repair method. Simply applying a bead of silicone caulk or concrete sealant for small hairline cracks is usually sufficient. Larger cracks may require using Expandable polyurethane foam (EPF), which expands as it dries to fill the crack and create a water-tight seal.
If the crack is large enough, you may need to install metal or plastic wall anchors to stabilize the area before repairing it. Wall anchors are driven into holes drilled along the length of the crack. Once in place, they’re expanded to grip the inside of the foundation wall and provide support. This is usually only necessary for cracks wider than 1/4 inch.
Once the crack is stabilized, it can be filled with EPF or concrete patching compound. The concrete patching compound will need to be smoothed out with a putty knife or trowel after it’s applied, while EPF will expand to fill the entire crack on its own.
After the repair material has had time to cure, you can seal the area with concrete sealant or silicone caulk. This will help protect your repairs and prevent water from seeping into the cracks in the future.
Preventing Cracks in Concrete Foundation Walls
The best way to deal with cracks in concrete foundation walls is to prevent them from happening in the first place. Here are some tips to help you avoid cracks:
- Make sure your gutters and downspouts are clean and free of debris. Clogged gutters can cause water to build up around your foundation, leading to hydrostatic pressure and cracks.
- Check the grading around your home and ensure it slopes away from the foundation. This will help keep water from pooling around your foundation and causing problems.
- Have your foundation regularly inspected by a qualified professional. They’ll be able to identify any potential problems before they become serious.
If you do find cracks in your concrete foundation walls, don’t ignore them. These cracks can quickly become major problems if they’re not properly repaired. By following the tips above, you can ensure that your concrete foundation will be strong and crack-free for years to come.
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