9 Causes of Foundation Cracks

Posted on: Sep 06, 2021


A horizontal foundation crack

Foundation cracks, however big or small, can cause worry for property owners. If you’ve seen some cracks in your home or if you are building for the first time, you may think that it could lead to structural collapse or other dire scenarios. Though this is a possibility, some foundation cracks are actually normal. 

So, how do you distinguish between normal cracks and cracks that need urgent intervention? It all ties back to the cause of the foundation crack.

In this article, we talk about various foundation crack causes and what you can do about them. Let’s begin!

Close-up shot of a leaking foundation crack

Construction-Related Foundation Crack Causes 

 Concrete Shrinkage 

Concrete shrinkage cracks are incredibly common. They look like hairline cracks that don’t usually span through the entire foundation wall. These cracks can appear as early as just a few hours after the concrete slab is poured.

The reason why concrete shrinkage cracks are so common is because they occur during the cement’s curing process. As water leaves the drying concrete, the volume changes and causes the concrete to shrink. The shrinkage generates tensile forces that can cause the cement to crack. 

The presence and prevalence of shrinkage cracks can be reduced during construction by making sure that your contractor does the following: 

 Cold Joints 

During construction, it is possible for delays to happen in between batches of concrete being poured for your foundation. The delay prevents the two batches from properly intermixing, resulting in a cold joint. Therefore, cold joints appear where one batch of concrete has already begun drying and when another batch is poured adjacent to it.

Cold joints aren’t technically concrete cracks but take on a somewhat similar appearance. Similar to cracks, cold joints can also allow water to leak through a basement’s wall or floor. 

Backfilling Too Soon During Construction 

Backfilling the surrounding areas of a newly constructed basement can have dire consequences. This is because concrete only reaches its full strength after around 28 days, assuming that the temperature is ideal for its curing process during that span of time. 

Backfilling too soon puts a load on the sides of concrete that isn’t ready for it, resulting in big horizontal cracks that have structural implications and will most likely allow groundwater to leak inside easily. This needs immediate repair.

Foundation Crack Causes Tied To Added Load

 Load From The Top 

Having added load on an area near your basement wall can lead to large cracks appearing over time. This added load can be in the form of a parking space, driveway, or something similar. The vehicles or heavy equipment that are usually stored in that area will push down on the soil near the basement, possibly creating lateral pressure against the basement wall.   Cracks like this need professional attention at once. 

Soil Loading

Earlier, we talked about backfilling a new basement too soon and how it can result in a lateral force that will make the new basement’s walls crack. However, even for older basements, soil can still exert a lateral force that can cause structural cracks to appear over time. 

For example, if the home is on a hillside or a terrain that slopes upward, the side of the basement that faces the upward part will have more lateral pressure from the soil. 

Another example of added lateral pressure from the soil is when soil with a high clay content expands, pushing against the basement wall. Cracks caused by this are typically horizontal and need professional intervention at once. 

Water Loading

Properties that are situated on high water tables can have foundations submerged in water. This causes hydrostatic pressure to push against the concrete and causes various cracks to appear. 

Unstable soil compaction can be another reason for water loading in the basement. This causes the loose soil to hold more water and when this water freezes and expands, it causes a lateral force to push against the basement wall. Furthermore, water in loose soil has a high chance of seeping through even the smallest cracks, hence forming puddles or floods.  

A puddle forming inside a basement

Other Foundation Crack Causes 

Earthquakes and Floods 

Earthquakes and extreme floods are two forces of nature that cause unusual stress on basement walls. These can both cause new cracks to appear or old cracks to become aggravated. If you see large cracks, it is best to call the pros to have them assessed in case they are tied to structural damage.  

Foundation Settling 

It is normal for a home’s foundation to settle within the first two years of its construction. This can cause small cracks. Uniform settling doesn’t cause structural problems. 

However, differential settling can occur when the underlying soil of the house settles at different rates. This causes damage to the basement, causing the formation of large horizontal or diagonal cracks. This needs expert attention at once.  

Plumbing Leaks 

Plumbing leaks near the basement can add water to the soil surrounding the basement, thereby increasing the lateral force on the basement walls. Though this may not immediately cause a structural crack, it can worsen existing cracks and/or flood your basement. Plumbing leaks must be remedied at once. 

How to Assess The Cause of Your Foundation Cracks 

Knowing your home’s construction history, your property’s topography, and recent stressors that your home has undergone will help you get an idea of why your basement has cracks. Some cracks may be normal and some are structural. Either way, they all come with an added pain point of basement leaks or floods.  

In some instances, crack repairs are enough. In other cases, you’d need more intensive repairs to the foundations (such as when it undergoes differential settling).

If you are concerned about persistent flooding in your basement, professional residential waterproofing can put a stop to it once and for all. 

Reliable Foundation Crack Assessment and Repair 

In this article, we’ve talked about various foundation crack causes. Depending on the cracks you have in your basement, you may have worries regarding structural implications, potential flooding, and so on. In any case, it pays to consult the pros. 

PRO Waterproofers is a Canadian waterproofing company known for its reliable service and innovative waterproofing solutions. We also specialize in foundation crack repair using durable and environmentally friendly materials. 

If you have any questions about foundation crack causes and repairs, feel free to reach out. You can also take advantage of our FREE in-home consultation by contacting us today

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