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Efflorescence on the interior basement wall.

Block Foundations: Cracks, Their Causes, & How to Repair Them

Block foundations are common the further north you go in the United States. Homeowners can benefit from understanding the pros and cons of these foundation types.

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If your home has a basement, it likely has block foundation walls. The simple design of block foundations mean it can support a ton of weight for a very long time. 

However, like all foundations, block foundations will sustain damage over time, and they come with their own set of weaknesses. In this article, we’ll cover the main causes of damage to block foundations and help you fight back against them.  

damaged cinderblock basement walls

What is a Block Foundation?  

As the name suggests, block foundations are made of cinderblocks stacked on top of each other and joined with mortar. An initial layer of masonry is built on foundation footings before the rest of the blocks are arranged. Not only does a block foundation support your home, but it also acts as a retaining wall – a barrier between the soil and your home. 

Most block foundations are constructed with concrete blocks, but some contractors may use compressed stabilized earth blocks that use materials such as limestone or sand mixed with concrete. Their high compression strength makes them just as strong as normal concrete blocks. No matter the material, all block foundations are constructed in a similar manner.  

Homeowners should also be aware that block foundations are NOT waterproof. Water leaks are always a possibility, especially in areas with high precipitation. In fact, this leads into the next important aspect in understanding block foundations. Let’s look at the biggest issues these kinds of foundations face.  

Cracks in Block Foundations

The most obvious forms of damage to your foundation are cracks. Because block foundations are made out of, well, cinderblocks, they usually crack along the mortar seams between the blocks rather than on the actual blocks themselves.

This means that the two most common crack formations in cinderblock foundations are horizontal cracks along one row of blocks and stair-step cracks that spread diagonally along multiple rows of blows.

What Your Basement Wall Cracks Mean

  • Horizontal cracks usually signal that your walls are bowing inward due to soil pressure pushing in from the outside.
  • Diagonal cracks usually signal that the ground beneath your foundation is beginning to settle. You can usually tell which side of your foundation is lowering because the the cracks leads upward towards whichever corner or side of the house is settling the most.

What Causes Damage to Block Foundations?

The natural forces of nature are actively putting pressure on your foundation. It all comes down to two things: soil and water. The cycle of soil getting wet and then drying out is kind of like a flexing muscle that puts pressure on your foundation in various ways.

The ever-changing combinations of the soil and and the amount of water in it act on your foundation in two ways: hydrostatic pressure and differential settlement. Let’s get a detailed look at each of these factors:

1. Hydrostatic Pressure   

Hydrostatic pressure is the force most responsible for basement wall damage. It’s really simple: as the soil fills with rainwater, the soil expands more and more, putting pressure on your basement walls.

Standing water in your yard is a sign that your soil is expanding, and high water tables can make it all the more important to address. If you live close to a lake or pond, be aware that hydrostatic pressure likely more of a problem around your home.  

Over time, hydrostatic pressure causes your foundation wall to bow outward or crack, but it can feel very sudden when your foundation finally shows signs of damage and water leaks into your basement. Moisture can attract pests of all kinds and contribute to unhealthy mold growth. 

Fun fact: hydrostatic pressure is what you experience when you go swimming or scuba diving and the pressure on your ears grows more and more as you dive deeper and deeper.

2. Differential Settlement 

Another issue that block foundations often face is foundation settlement. Simply put, this is when a foundation is no longer supported by the soil below it. Water (or lack of it) also plays a major factor in this issue. There are three main reasons settlement occurs:  

  • Soil is too wet 
  • Soil is too dry 
  • Soil is not compacted tightly enough 

When soil becomes oversaturated by precipitation, it becomes soft and squishy. Your heavy concrete block foundation will sink into wet soil like your foot does when you step into mud.  

Even though drought is not a common occurrence in DC, Virginia, and surrounding areas, it can also cause soil to become unsupportive. Dry soil shrinks in size, becomes brittle, and cracks under the weight of your foundation.  

Lastly, poor compaction can cause soil to be weak. When soil particles are not packed tightly enough, small pockets of air cause structural integrity issues and your foundation once again sinks into the weak soil.  

No matter the cause of soil issues, your block foundation walls are always going to be too heavy for the weakened soil. Thankfully, JES Foundation Repair has plenty of options to combat the effects of foundation settlement.  

How to Protect Your Block Foundation 

JES Foundation Repair has the tools necessary to keep your foundation walls protected no matter the cause of damage. We’ll outline the solutions we use for both hydrostatic pressure and settlement, so you know exactly what to expect when it comes to repairs.  

1. Basement Waterproofing 

Basement waterproofing includes a few different solutions that work in tandem to keep your basement dry and strong simultaneously. First, our team will install wall anchors to straighten out any bowing walls and protect them against building pressure in the future.  

Wall anchors are installed into unmoving soils away from your foundation so they offer permanent protection, and they also close any cracks that may be causing leaks. However, this doesn’t keep all the water out.  

Our team will also recommend using dehumidifiers, interior drainage systems, and sump pumps to keep water out and move any moisture away from the foundation. With these options working side by side, your basement is well defended against hydrostatic pressure.  

2. Pier Systems  

Since settlement is caused by weak soil, JES Foundation Repair uses pier systems that support your home and foundation without relying on the soil. Piers come in three varieties, each with its own unique design. However, they all accomplish the same goal – stabilizing your foundation. Our piers include: 

All our pier systems implement a similar basic design, with slight design differences depending on the style. However, all piers use a long, galvanized steel rod that is inserted below the ground into sturdy, load-bearing soils such as bedrock. These soils are unaffected by moisture-related issues. Plus, the piers push any uneven portions of your foundation back into place, restoring your home to its proper form and closing cracks in the process.  

An added bonus is that installation is minimally invasive to your property as the piers rest underground. Our team is dedicated to thoroughly cleaning up your yard after installation and taking care to keep your landscaping pristine.  

Dedication to Quality Service 

Since 1993, JES Foundation Repair has been helping homeowners keep their foundations in prime condition. If your basement walls are experiencing cracks, leaks, or any other damage, we can help.  

Our team of experts is ready to inspect your home and determine the best solution to the problem. Whether you’re currently dealing with foundation damage, or you want to protect against issues arising in the future, contact us today for a free estimate – we’re here to help.  

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JES Foundation Repair service area map of the Mid-Atlantic region.

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8361 Town Center Ct
Nottingham, MD 21236


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Suite 2-02
Fredericksburg, VA 22401

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Bristow, VA 20136


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Ashland, VA 23005

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Salem, VA 24153

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Appomattox, VA 24522


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Winchester, VA 22601