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How to Fix Foundation Cracks


Terry Kobatskyi

Terry Kobatskyi

Terry is a reliable project manager with over 15 years in construction field, who has started his career of working in the trenches. Learn More About Terry Kobatskyi

A sturdy property is directly linked to its foundation. However, concrete foundation cracks are not always indicative of grave issues and can be addressed effectively once understood. 

We’ve curated a comprehensive guide for you, outlining the various types of concrete cracks, their consequences, and providing a detailed, step-by-step approach to effectively repair them.

Step 1: Identify the type of crack

The type of crack within the foundation could either be a hairline crack, a minor to moderate crack less than 1/8 inch wide, or a significant crack that’s more than 1/2 inch wide or reveals a shifting pattern.

Step 2: Determine the action needed

Can I fix a foundation crack myself?

If you see a big crack in your foundation that’s wider than half an inch, it’s a good idea to have a professional check it out.

The foundation’s situation would dictate how you should proceed. Hairline cracks usually require no treatment. Minor to moderate cracks that don’t expand can often be addressed with a simple DIY fix, while significant cracks need professional input.

Step 3: Grab the necessary Supplies

Once you’ve established the action plan, gather the supplies needed for the job. This may include masonry paint for hairline cracks, and concrete filler or sealant for minor to moderate cracks. Major cracks would need a professional who would use expert grade materials and techniques.

Now, let’s walk through the process of repairing minor to moderate cracks:

Step 4: Clean the Crack

To prepare for the repair, start by cleaning out any loose concrete, dirt or debris with a wire brush to ensure a smooth surface for the sealant.

Step 5: Apply the Concrete Filler

Next, apply the concrete filler into the crack. It’s crucial to fill the crack entirely with the sealant from the bottom up to work out any air bubbles. Directly apply the sealant if the tube does not have an applicator. Otherwise, cut the applicator tip at a 45-degree angle and load into a caulk gun for application.

Step 6: Smooth out the Sealant

Use a putty knife to smooth out the sealant once it is filled. Overfill the crack slightly so that the sealant stands out a little bit over the concrete surface. 

Step 7: Let it Dry

Allow the sealant to dry based on the specific instructions on the product. Drying times can vary, but expect it to take several hours at least.

Step 8: Sand the Surface

Once the filler is dry, sand the excess with medium-grit sandpaper to make sure the filler is flush with the rest of the concrete surface.

Step 9: Paint over the Repair

If necessary, paint over the repaired area with a primer and paint that matches your concrete to conceal the repair work.

Aquatech Waterproofing

When it comes to safeguarding your home’s foundation, remember that prompt action is essential. Even the slightest sign of a crack should not be ignored, as addressing it early can prevent more costly repairs down the line. 

In case you encounter substantial cracks, it’s crucial to consult a professional, as they could signal a more serious underlying issue. For expert guidance and assistance in foundation protection, consider reaching out to Aquatech Waterproofing!

FAQs About Foundation Cracks

There is no “acceptable” amount of foundation cracking. Any crack in the foundation should be evaluated to determine its significance.

You should worry about cracks in the foundation when they are wide, diagonal, or exhibit signs of movement, as these could indicate structural issues.

Wide, diagonal, or vertical foundation cracks are often considered more concerning, as they may signify structural problems, while narrow, hairline cracks are usually less worrisome.

Generally, any foundation crack larger than 1/8 inch (3mm) is considered a potential problem and should be assessed by a professional.

Structural cracks often show signs of movement, such as a diagonal pattern, separation, or uneven displacement of foundation sections. If you suspect a crack is structural, consult a professional for an assessment.