If concrete does one thing, it’s crack. Thus, most basement floors will develop small settlement or hairline cracks over time. However, not all cracks in basement floors are harmless. As a homeowner, there are a few floor crack characteristics that could indicate structural damage that you should keep an eye out for.
In this guide, we’ll discuss everything you need to know about cracks in basement floors—including types of floor cracks, causes, and repair solutions.
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Are Cracks in Concrete Floors Normal?
The short answer is yes—cracks in concrete floors are normal, if not inevitable. As concrete cures, it will naturally develop tiny cracks as the mix dries and water evaporates. Over time, your concrete basement floors may also crack due to uniform settlement. These cracks will typically be narrow and won’t be accompanied by signs of structural damage, such as cracks in walls and sticking doors and windows.
That being said, there are certain types of basement floor cracks that do present a cause for concern. When the cracks in your basement floor are larger than an eighth of an inch, grow over time, have caused the floors to be uneven, or are accompanied by other signs of damage, it could be a sign that your foundation is damaged as well.
What Do the Cracks in Your Basement Floor Mean?
Typically, the distinguishing factor between normal and concerning basement floor cracks are the crack’s size. There are three different size categories that the cracks in your basement floor likely fall under: hairline, between 1/16-inch and ⅛-inch, and larger than ⅛-inch.
1. Hairline Floor Cracks = Shrinkage
Concrete is comprised of cement and water. As concrete cures, the cement will harden and the water will evaporate, causing shrinkage. How much the concrete sinks will usually depend on temperature, how well the concrete was mixed, and whether or not it has been reinforced underneath the slab. These factors will determine how quickly the concrete dries—the more rapidly the concrete cures, the more likely it is to shrink. Though there are methods of pouring and curing concrete that can reduce shrinkage, there’s no way to completely avoid it. However, shrinkage cracks are nothing to worry about, and can be easily sealed to improve aesthetic appeal.
2. Floor Cracks Between 1/16-inch and ⅛-inch = Uniform Settlement
Most homes will settle as the soil supporting the foundation gives in to the weight of the structure. Normal settlement will occur slowly and evenly, meaning one part of the house won’t sink significantly lower than another. Most foundations are built to withstand normal settlement—anywhere from one to four inches over a given number of feet, depending on the soil and slope of the land. This type of settlement may cause narrow cracks to form across basement floors. As long as these cracks don’t get larger over time and aren’t accompanied by other signs of structural damage, it should be sufficient to have these cracks leveled and sealed to prevent water leaks.
3. Floor Cracks Larger than ⅛-inch = Differential Settlement
Differential settlement, as opposed to uniform settlement, can cause severe structural damage and lead to large floor cracks accompanied by drywall cracks, misaligned doors, and sloping floors. Differential settlement can be caused by a number of soil disruptions, including expansive soils, soil washout, and poorly compacted fill soil. Because differential settlement causes the foundation to heave or settle unevenly, large cracks and structural damage can occur. Unfortunately, these issues will only worsen over time and thus need to be addressed sooner rather than later.
Differential Settlement and Basement Floor Cracks
Differential foundation settlement is an issue that can start off as a small problem and eventually serve as a catalyst for larger issues in your home. A large crack in your basement floor may be the first indicator of differential settlement or the confirmation that other signs throughout your home are pointing towards structural damage.
Other Signs of Differential Settlement
Signs of foundation settlement in Georgia are cracks in your foundation floor, dropping floors and separating walls, gaps between floors and walls, walls pulling down and separating from the adjacent surfaces, and, most noticeably, vertical or stair step wall cracks along the exterior/interior of your home.
What Causes Settlement That Leads to Cracks in Basement Floors?
The soil underneath and surrounding your home is the primary cause for concrete and foundation settlement in Georgia. Foundation settlement is basically the result of the movement a home experiences when soil forms void pockets due to washout or dry-out and subsequent soil erosion. That void-laden soil can simply no longer support the heavy weight of the concrete or foundation walls that sit atop it, and so the slab or walls will gradually crack and shift downward, or settle, into those voids.
The three most common causes of settling concrete floor slabs are as follows:
In Georgia, we have a type of soil referred to as Georgia red clay. Being an expansive soil in nature, Georgia red clay expands when it’s oversaturated and shrinks after extended periods of drought. As this soil continuously expands and contracts due to Georgia’s ever-changing climate and temperature, it can erode away, leaving air pockets called voids.
Soil Washout due to Plumbing Leaks
Although soil washout is typically caused by improperly-channeled rain water, plumbing leaks can also serve as a catalyst for soil washout and erosion. Plumbing leaks can stream underground due to inadequate drainage. In either case, water breaks down soil and causes it to wash out and erode away from under the foundation. With a void underneath the floor, there’s nothing supporting the concrete slab anymore. In time, it begins to crack basement floors, leading to both concrete and foundation settlement.
Poorly-Compacted Soil or Loose Backfill Dirt
When your home was built, a big hole was dug into compact virgin soil to make room for the house. During this excavation process, layers upon layers of soil are commonly moved around or spread out to get to the desired grade level during new home construction. Once graded, the footing is poured, then the foundation walls (if you have a basement), then the concrete floor, and finally the rest of the house is built on top. Lastly, loose backfill soil is poured back in around your foundation walls. If poorly compacted, or if accompanied by an inadequate drainage system, this loose backfill soil can wreak havoc on your home’s slab floor or foundation walls. As mentioned above, the fill soil is highly-susceptible to washout or dry-out and expansion or contraction over time, which can create voids and cause settlement issues.
So you see, no matter what the specific reason, the cause of concrete settlement is ALWAYS the soil.
Risks of Having Cracks in the Basement Floor
Not only are basement floor cracks unattractive, they can also be signs of even bigger issues—foundation problems. If ignored, these problems can lead to weak foundation walls and a wet basement. Here’s what can happen if you neglect cracks in your basement floor:
Any cracks in your basement floor have the possibility to leak and cause water seepage. The ground underneath your foundation is full of moisture, so when there are cracks in the foundation, it lets pressure force the water up into your basement. Once moisture exists in your basement, bigger problems like mold and bacteria growth can begin to form, causing serious health hazards for you and your family.
For the most part, concrete basements will always crack. Fortunately for most homeowners, small cracks from shrinkage rarely impact the structural integrity of the home. That is not so true for larger cracks, which is caused by instability of the soil beneath the home. It’s important to be able to identify the bigger floor cracks because it can lead to serious issues. If you notice significant basement floor cracks, have them inspected right away by a professional to assess the potential for greater damage.
There are plenty of unwanted pests, such as mice, rats, and cockroaches that thrive in dark, damp environments like a basement. When there are cracks in the foundation or basement floors, it can become an open invitation for these undesirable house guests to invade your home. Don’t wait, call AquaGuard Foundation Solutions today for a free inspection before you have to share your home with all sorts of critters!
How to Fix Cracks in Basement Floors
At AquaGuard Foundation Solutions, we take into careful consideration the kind of basement floor crack present and the cause of damage before we recommend a repair method. It’s important that the solution fixes the problem at its source. Depending on the damage present, we offer two types of basement floor repair methods:
1. Slab Pier Systems:
For basement floor cracks caused by differential settlement, we install a slab pier system that connects the slab to stable soil or bedrock. Once installed, the system makes it possible to re-level settled slab sections. Slab piers systems stabilize the foundation and prevent the possibility of further differential settlement.
To install our patented slab pier system, our contractors will take these six steps:
Preparing for installation
Before installation of our slab pier system, a representative from AquaGuard will visit your property and inspect your basement floor cracks.
At that time, a foundation repair proposal will be put in writing along with a map of where the slab pier locations will be installed.
At the beginning of each slab pier installation, a small hole is cored specifically at each mapped position through your concrete slab floor. This hole will create an access point for the slab piers that are about to be installed.
Positioning the Slab Bracket
The Foundation Supportworks Slab Pier System utilizes a unique three-piece slab bracket that is assembled underneath your concrete floor, allowing for a much smaller and concealed hole to be cored in your concrete slab.
Additionally, the larger the bracket, the more surface area it covers, allowing for an equal distribution or spread of the load.
Steel Tube Installation
Steel tubes are then hydraulically driven or advanced deep into the ground, past any troubled soil that may have been causing your foundation issues beforehand. This way, once installed, your slab will be supported by strong, competent soils. To ensure the quality and long-lasting strength of your slab pier system, these steel tubes are designed with galvanized steel to resist corrosion. These tubes are the real strength of the foundation pier system and are responsible for transferring the home weight to strong supporting soils.
Transfer Slab Weight to Soil
With the brackets and tubes installed and in place, the weight of the concrete slab is transferred through the piers down to the load-bearing strata far beneath your home.
As the system lifts your concrete slab floor upwards, the sinking movement of your floor will be permanently halted and releveling the slab will become possible.
Inject Grout Fill
Once the concrete slab has been lifted, a void will be present underneath the floor.
Additionally, if your floor was sinking because of compacted soil or washout, a gap existed even before the installation.
To address this, we carefully pump grout under the slab to fill in all empty spaces.
At AquaGuard Foundation Solutions, we take pride in leaving your home looking clean and neat. Once the installation is completed, we repair all cored holes neatly with concrete, making your final installation virtually invisible.
Any debris generated during the installation is cleaned up and removed by us. And once we’re done, you can rest easy, knowing that you have a 25-year warranty on manufacturer’s defects, as well as a performance warranty from us.
2. Basement Floor Crack Repair Epoxy and Concrete Leveling Injection Foam:
For nonstructural basement floor cracks, AquaGuard raises settled concrete using PolyLevel™ expanding foam. Injecting this high-density, structural-grade, polyurethane foam beneath the slab fills voids and stabilizes weak soil, while simultaneously providing the most accurate opportunity on the market to raise settled slabs back to their original position.
Unlike antiquated slab-raising methods like MudJacking, SlabJacking, or Pressure Grouting – which all require pumping a heavy slurry or grout into the soil that can weight as much as 100-140lbs per cubic foot, PolyLevel™ is only 2-4 lbs per cubic foot and thus will not add noticeable additional weight to your home. Even more importantly, PolyLevel™ and will fill any sub-slab voids and hold, regardless of whether the slab was poured properly initially or not, as PolyLevel™ is completely waterproof and inorganic (will not decompose over time). Hence, PolyLevel™ permanently stabilizes the soil beneath your slab. This is vital, because as is the case with all foundation repair issues, the real problem is the soil settlement itself—and the soil is often overlooked entirely with the aforementioned alternative repairs.
Basement Floor Crack Repair Methods to Avoid
Unfortunately, not all basement floor crack repair solutions are effective. If your basement floor cracks point to a structural issue, it’s important to have one of our in-house foundation repair specialists fully inspect and analyze your foundation before any repairs are made. Foundation damage is a serious issue, and some methods of repair are expensive, disruptive, or ineffective.
Here is one basement floor crack “repair” method we do NOT recommend:
In order to conduct a concrete slab replacement in your home, all home furnishings, floor coverings, and interior partition walls must first be removed from the home. Then a jack-hammer crew breaks the existing floor slab into small pieces and removes each piece from the home by hand.
Then, a new floor is poured and allowed to cure for at least two weeks. After the floor has cured, interior partition walls can be re-built, floor coverings re-installed, and home furnishings brought back in.
While this situation is obviously disruptive and expensive, the real problem isn’t even addressed! The floor isn’t the problem—the soil beneath the ‘new foundation slab’ is the problem. A concrete slab replacement is ineffective because it’s basically a brand new concrete foundation over the same troublesome soil. So you can expect that your new floor will crack just like the old one did.
We Can Permanently Stabilize Your Home!
You shouldn’t be concerned with or have to live in fear of your foundation walls collapsing. With a simple call to AquaGuard Foundation Solutions, we can quickly identify the cause of your home’s structural/foundation issues, as well as the necessary solutions to permanently stabilize your home! Each of our repairs permanently resolves your issue and are backed by national, transferable, life-of-structure warranties, and we put that in writing! With us, our ultimate goal is your peace of mind.
If you would like to contact us for a free foundation slab stabilization quote to identify and address your foundation problem, call or e-mail us today!
Our service area includes Metro Atlanta and all cities throughout Northern Georgia, including Athens, Gainesville, Dahlonega, Cumming, Blue Ridge, Rome, Cartersville, Carrollton, Peachtree City, and Conyers.