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How To Repair Your Concrete Foundation That’s Crumbling

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If you want to know how to repair your concrete foundation that’s crumbling, you’ve landed on the right page. Most homes in the United States are built with basements, crawl spaces, or slab foundations made of concrete. Unfortunately, concrete is not invincible to the elements, especially water. This article will give you an in-depth understanding of why concrete crumbles, how to repair the damage, and how to prevent it from happening in the future.

Why Is Your Concrete Foundation Crumbling?

Your foundation is most likely crumbling because trapped water is freezing and thawing inside the concrete. Concrete foundations in hotter areas that don’t experience freeze-thaw cycles are usually crumbling because of improper water mitigation and built-up groundwater. Professionals call this scaling or spalling. This may look like a simple cosmetic issue at first, but over time, the smaller chips and crumbles can grow larger, spreading across your foundation. Here’s why.

Freezing and thawing

Concrete is a porous material and will absorb water. If water gets inside your concrete and freezes, it pushes the cement binder apart. This expansion, combined with the contraction when the water melts, causes the concrete to crumble. If you live in an area that experiences freezing, look into concrete sealers and foundation waterproofing.


If you have an older foundation, there’s a chance the aggregates inside the concrete have high amounts of pyrite, silica, and mica. Modern concrete testing can determine if your concrete has these minerals, but older foundations may have gone unnoticed. These minerals can oxidize near the ends of the concrete, leeching out and causing crumbling.

De-icing salt

(colder regions) – If you throw salt on your driveway during winter to melt snow, make sure you don’t get any on your foundation. Rock salt (sodium chloride) will react with your concrete, causing pitting, scaling, and crumbling. This will also happen to your concrete driveway if you use it every winter. Try alternative de-icing crystals like magnesium chloride or potassium chloride.

Too much water

If builders add too much water into the concrete mix during construction, the chemical bonds that create a solid and durable surface will weaken. Builders or homeowners who use concrete should always use the proper amounts of mix and water.

How To Repair Your Concrete Foundation That’s Crumbling

1. First, remove dust and loose concrete from the crumbling area using a stiff scrub brush. Use a chisel, hammer, or rotary hammer with a chisel top to remove larger crumbling pieces (save these for later). Only remove concrete that is already cracked, keeping unaffected concrete intact. If there is exposed rebar, you need to remove all traces of rust from the steel using a wire brush followed by pressure washing.

2. Use a garden hose and scrub brush to clean away dust and lose particles. Wait 24 hours for the concrete to dry before you move to the next step. (Also, make sure there is no frost on the concrete.)

3. After 24 hours, wet the concrete using a sponge, brush, or spray bottle until it’s slightly damp. Do not soak the concrete.

4. Apply a cement paint or adhesive primer to the concrete before the patching material. This allows the patching material to bond to the old concrete. If you want to make your own cement paint, mix Portland cement with clean cold water until it’s like latex paint. Once it’s made, apply the paint using a medium or large paintbrush.

5. Immediately after you’ve applied the cement paint or primer, apply the patching material. This ready-mixed concrete patching compound can be found online or in your local home improvement store. Place the pieces of concrete you saved into the larger empty spaces along with the patching compound. Try to work when the sun is down if you are outside. Sunlight, wind, rain, or frost can affect the patching compound and ruin the repairs.

6. After two hours, apply a second layer of patching compound, ensuring the concrete is smooth and level. Let the compound cure in the open for 30 minutes.

7. Cover the newly patched concrete with a plastic tarp, lightly spraying the repaired area with water once a day for two days. Once the compound has cured, remove the tarp and pat yourself on the back. You’re done!

How To Prevent Your Concrete Foundation From Crumbling In The Future

The main reason concrete foundations crumble is due to water exposure or saturation. This can happen if water directly touches your foundation or the soil next to your foundation is filled with groundwater. The best way to counter water buildup is by directing it away from your foundation using drainage systems, such as drain tiles, French drains, gutter downspout extensions, and grading.

Who Can Help?

While water and freezing issues are not typical for homeowners in Southern California or Central Arizona, Dalinghaus Construction can still help if it happens to your home. We believe preventative maintenance is the best form of maintenance. If your concrete foundation is crumbling, get in touch with us as soon as possible before the problems spread throughout your home. If you would like a free inspection from one of our foundation specialists, call today.


Brian Dalinghaus

Brian is one of the Co-Founders of Dalinghaus Construction. He has been in the foundation repair industry since 2005. During his career, he has been associated with helping over 4,000 homes and structures throughout California and Arizona.

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2 Responses

  1. Enlisting the help of a foundations expert when doing concrete repairs could make all the difference. If I don’t have someone like that helping me, I could make mistake after mistake and end up causing more trouble for my house than intended. I’ll go and look for a foundations expert in the area so they can assist me with what I need.

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