How To Repair Foundation Cracks (2025)

By Amanda Lutz Updated February 5, 2024

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Foundation cracks can compromise the structural integrity and safety of your home. Identifying and addressing the issue promptly prevents further deterioration and costly repairs. You may notice foundation cracks in your basement wall or crawl space. Sometimes, they’ll be more evident through settling and drywall cracks inside your home. Our guide below covers the immediate steps to take to safeguard your property and secure your living environment.

 

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Foundation Cracks

Understanding the difference between structural and non-structural cracks is an essential first step. Structural cracks are wider than 1/4 inch and can cause damage to other parts of the house. Non-structural cracks are typically narrower and don’t have as much of an impact.

For DIY enthusiasts, epoxy injections and hydraulic cement patches may fix minor issues until a professional can be consulted. If the cracks you notice are not structural, there’s a good chance the home has good bones. You can still improve cracks cosmetically without worrying about the foundation.

 

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Assessing Your Foundational Crack

To accurately assess the type of crack, examine the following characteristics closely:

• Accompanying symptoms (moisture intrusion or bowing walls)
• Direction (vertical, horizontal, diagonal)
• Length (short versus extensive)
• Location (interior versus exterior)
• Presence of displacement or bulging
• Width (hairline versus wider gaps)

Minor vertical hairline cracking may not require professional intervention if no other signs point to significant damage. Monitor them to see if they spread or get worse over time.

If there are cracks in your foundation, ask the following questions:

• Are there other signs of damage accompanying the cracks? These could include doors and windows that don’t open or close properly, sagging or uneven floors, or cracks in the walls and ceilings.
• Are they horizontal or diagonal? These cracks often indicate serious structural problems and can lead to significant damage if not addressed promptly.
• Are they larger than 1/8 inch wide? Wider cracks can indicate more severe problems, such as soil shifting beneath your foundation.

 

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Gathering Supplies

Gather suitable materials before repairing foundation cracks. Depending on the type of crack, you may need different supplies to address the issue effectively. Here are some essential materials you may need:

• Caulk gun: A caulking gun is an indispensable tool for injecting epoxy or polyurethane resin into narrow fissures.
• Epoxy or polyurethane injection: These specialized resins can be injected into fine hairline cracks in concrete foundations. They provide excellent adhesion and help seal cracks from water penetration.
• Hydraulic cement: Ideal for larger foundation cracks, hydraulic cement expands as it cures, filling up voids and tightly sealing the damaged area.
• Masonry patching compound: If your foundation has minor surface cracks or spalling, a masonry patching compound can be applied to fill these imperfections and restore structural integrity.
• Wire brush or chisel: Clean loose debris from the crack using a wire brush or chisel before applying repair material. This step ensures better adhesion and helps remove any crumbling portions of concrete that may hinder proper repairs.

Note that different foundation cracks require specific approaches and materials for long-lasting results. For example, hairline cracks often benefit from epoxy or polyurethane injection methods due to their ability to penetrate deeply into narrow gaps and create a strong bond across multiple layers of concrete.

 

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Prepping Cracks for Repair

To ensure the best repair for your foundation cracks, thoroughly clean the crack using a wire brush or vacuum cleaner. Then, widen the gap with a hammer and chisel to create bonding space for the repair material. Be cautious not to overdo this process, as it may weaken the surrounding structure.

After widening, use compressed air or a damp cloth to remove any dust or debris caused by chiseling. Scrutinize the cracks to detect additional needs, such as filling voids or injecting epoxy resins. Before applying sealant or patching compound, ensure all surfaces surrounding the crack are moistened but not saturated with water. This helps secure proper bonding between new and existing materials while preventing premature drying of applied compounds.

If your foundation crack has caused settling inside your home, you might find some cracking in your drywall and plaster. Repairing plaster is a simple project.

 

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Repairing the Foundation Crack

Cracks on a home’s foundation come in various shapes and sizes. We’ll explain the most common foundation cracks and how to repair them below.

Diagonal Cracks

Clean the area around a diagonal crack in your foundation with a wire brush and vacuum to remove debris. Widen the gap slightly with a chisel or angle grinder to create a V-shaped groove for better adherence. Inject an epoxy or polyurethane filler into the groove as instructed by the manufacturer. Let it dry, smooth excess material, and paint over it for an even finish. Check the foundation regularly for new cracks and address them quickly to prevent further damage.

Hairline Cracks

If you notice a thin break in your foundation, take care of it immediately to avoid further damage. Clean the area surrounding the crack with a wire brush and vacuum up debris. Use a caulk gun or syringe to inject an epoxy/polyurethane material into the crack until it is filled. Let the product dry by following the manufacturer’s instructions, and use a putty knife to clear away any excess material. Monitor the repaired crack for stability and contact a specialist if you see any signs of expanding or recurring cracks.

Horizontal Cracks

To repair a horizontal crack on the foundation, assess the damage first, scrub the crack with a wire brush, and remove any loose material or mortar. Inject epoxy or polyurethane into the crack to seal it. Give the material time to heal before looking for signs of cracks or water leakage. If needed, consult a professional contractor.

Stair Step Cracks

A stair-step crack is a common form of foundation damage that looks like a set of stairs. Analyze the severity and decide if professional help is needed. DIY repair is possible with epoxy or polyurethane foam if the crack is slight. However, these approaches may only provide temporary fixes. Consult a specialist for long-term stability and prevention of further damage.

Vertical Cracks

To fix a vertical crack in your foundation, clean the crack of any debris or dirt using a brush or vacuum. Then, apply an epoxy or polyurethane injection filler as instructed by the manufacturer. Give it enough time to dry and cure. Watch for signs of recurrence or the need for further repairs.

 

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Sealing the Repaired Crack

Select a high-quality, flexible sealant explicitly made for foundation repair to seal the repaired crack properly. Clean and dry the damaged area before applying the sealant with a caulk gun or trowel, filling in the gap and smoothing any excess. Let the sealant dry completely according to the manufacturer’s directions before taking other steps to complete your foundation repair.

 

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Preventive Measures to Avoid Foundation Cracks

Here are some measures you can take to prevent foundation cracks:

• Avoid planting large trees close to your home: While trees provide shade and beauty to any landscape, they can also cause significant issues if planted too close to structures or utility lines.
• Control irrigation practices: Opt for sprinkler systems with adjustable settings based on weather conditions. Avoid spraying directly onto concrete surfaces near your foundation to prevent oversaturation of the soil and potential damage.
• Grade away from the foundation: Ensure a gentle slope that directs water away from the house to prevent pooling or seepage near vulnerable areas.
• Install landscaping features: Consider strategically incorporating landscape elements such as flower beds, shrubs, and trees around your property’s perimeter. These can act as natural barriers against water runoff and help regulate soil moisture levels by absorbing excess rainwater.
• Maintain proper drainage: Regularly clean gutters, downspouts, and drains to prevent blockages or water accumulation around the foundation.
• Monitor soil moisture levels: Keep a close eye on the moisture content of the soil surrounding your foundation. Excessive dryness or saturation can cause the soil to shrink or expand, leading to stress on your foundation walls. Utilize a moisture meter or consult with professionals to determine optimal moisture levels for your soil type. You may benefit from crawl space encapsulation if you have a crawl space.

 

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DIY vs. Pro

DIYers with some experience can often handle minor cracks (less than 1/4 inch) when repairing foundation cracks. For larger and more severe cracks, we recommended calling a foundation repair specialist. Their expertise and equipment allow them to accurately assess damage and provide long-lasting solutions for the safety of your home.

 

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Our Recommendation

Be cautious and consider the extent of the crack before attempting to repair it. We recommend consulting a certified structural engineer or qualified foundation expert to assess the situation.

DIY solutions, such as epoxy injections or concrete crack sealants, can be applied to minor cracks with no signs of shifting soil or structural damage. In cases where the cracks are deeper and more severe, licensed contractors who specialize in foundation repair should be consulted. More advanced repair methods might be necessary for extensive cracking from external factors, such as water infiltration or inadequate drainage systems.

 

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