Main causes of cracks
Shifting and tilting of the building
One common cause of the crack is the settlement, shifting, or tilting of a building. This usually occurs when the soil beneath the foundation shifts or compresses due to external forces, such as natural disasters, improper drainage, erosion, overloading with water/rainfall, and the effects of gravity. When soil compresses under heavy load, it exerts pressure on the building. Excessive load on the ground around a foundation results in extreme compression of soils and downward structure movement.
Eventually, gravity will take its toll, and the building shifts or tilts to relieve that pressure into the surrounding soil. This shift inflicts severe stress on basement floor concrete, causing cracks, often at places like the corners or edges of the basement floor.
Tilting of great magnitude can cause major cracks in the basement floor, leading to the collapse of the building over time unless it is supported by proper bracing or underpinning. This problem also occurs when settling soil causes uneven pressure on the foundation of a building, eventually shifting its position and distorting the shape of outer walls resulting in severe damage.
Another common cause is water erosion that sends continuous underground rushing waters underneath concrete floors, causing severe decline, sometimes cracking under foundations. Harsh chemicals often used for de-icing roads in winter may seep into nearby soil and weaken it around foundations, resulting in de-compaction (a process where force compacts soils) and concrete fracturing.
The most common cause behind basement floor cracks is poor workmanship while constructing or renovating a building. Poor and untimely backfilling (refill of excavated soil) around foundations may allow water to accumulate inside, which would expand and exert pressure on the grounds, resulting in cracking under the foundation.
Excessive dumping of fill dirt into excavation sites may also cause severe problems with the structural stability of a basement floor if it does not follow load-bearing guidelines set by engineers during the planning stages of construction.
Basement wall’s weak structure
It is important to note that a structure’s solid and stability depends mainly on its weakest link. The inherent weakness in basement wall systems is their inability to bear stress at all points uniformly. This is because of the less compacted soil used to construct these walls and their inability to sustain heavy loads. These results in instability and cracking, mainly if built many feet below ground level and relatively close to shifting soils.
Basement floor cracks solution
There are several ways to prevent & solve basement floor cracks problems during excavation, construction, or renovation work.
- They are excavating deep enough to reach strong, compacted soil layers.
- Provide proper reinforcement for weaker zones by adding steel rods, Reinforcing mesh, or welded wire fabric before pouring concrete floors.
- Constructing adequately thick outer walls using appropriate thicknesses of reinforced cement concrete (RCC).
- It uses inner columns made out of brick masonry or solid/strong materials at least one ft. thick to carry a load of outer walls.
- Designing floors to suit the load they are likely to bear by consulting an engineer or technician during the planning stages.
All these procedures should be followed carefully to ensure that excavation work doesn’t lead to severe problems, such as sinking or tilting buildings.
Cracks in basement floor concrete may also result from other factors, such as natural disasters and earth tremors felt a few miles away from a structure site. In most cases, however, cracks occur due to poor workmanship during construction/renovation or bad foundation design that does not consider weak soil areas when building a structure on them.
The sealing of cracks in the basement floor
The best method of sealing cracks in the basement floor is with an epoxy or urethane sealer that will cure into a thin, solid sheet. Since these materials are applied very thick (usually about 1/2”), they do not readily release gas like other caulk-type products like silicone.
Even if your crack is within your cement slab setting bed, you could get measurement variance, use at least 2” thickness, you can always tape over it after applying (a thin bead around the outside edge). Also, any electrical penetrations should be sealed as well. You might want to check under your sink and water heater where plumbing enters the house. The basement is DRAINBO vented.
Sealing basement floor cracks at the base of a shower wall for radon
You need to apply a material that will cure into a thin solid sheet. About 1/2” thick is what you would be looking for. Epoxy or urethane sealers are excellent choices. Since these materials are applied very wide, they do not readily release gas as silicone caulk does even under pressure from any leakage.
If your crack is within your cement slab setting bed, you could have some deviation in results. Use 2” thickness as a minimum; Use tape over if necessary, after applying (thin bead around the outside edge). Any electrical penetrations should be sealed as well. If your basement is vented, there are “radon downdraft systems” that can be installed to take care of this problem.
What should I use to patch the cracks in my basement floor?
Making ensuring there are no gaps or inconsistencies, and fixing the crack with a piece of concrete. Employing a putty knife, smooth the patch. If a second patch is necessary to repair the damage, wait until the first coat has dried before applying the second. After sealing the concrete repair, let it cure for several days.
Should I worry about cracks in my concrete floor?
If you have noticed cracks in your concrete floor, you may wonder if you should be concerned. While some small cracks are normal and do not indicate significant damage, more extensive cracks can cause worry. General cracks in concrete floors can be caused by various factors, including settling or shifting of the foundation, changes in temperature or moisture levels, or even heavy loads or impacts.
Minor cracks, such as those less than a quarter inch wide, may be a cosmetic issue and not affect the structural integrity of your floor. However, larger cracks, particularly those that are wider than a quarter inch or that appear to be spreading, may indicate more serious damage that needs to be addressed. Additionally, cracks that are accompanied by other signs of damage, such as sinking or sloping of the floor, may indicate a larger foundation problem that requires professional attention.
In short, while small cracks in your concrete floor are generally not cause for concern, more extensive cracks may indicate a more significant issue that requires attention. If you are uncertain about the severity of the cracks in your floor or if you notice any other signs of damage, it is always best to consult with a professional to determine the best course of action to protect your home and ensure the safety of your family.
Is it essential to pay attention to cracks in the basement floor?
A crack with heaving indicates a more significant problem that must be addressed. Soils with clay are prone to heaving. Basement floor damages combined with heaving are concerning. Heaving demonstrates that the ground beneath the basement floor is expanding.
What is the cost of repairing a cracked basement floor?
Repairing a foundation can cost as little as $500 for minor cracks and as much as $10,000 or more if hydraulic piers are required. Foundation repair costs average between $2,000 and $7,000 for the average homeowner.
Can cracked concrete be covered with carpet?
To cover them with carpet, you must repair the cracks. Otherwise, they will show through the carpet and, over time, will damage the carpet backing. Moreover, moisture will cause the adhesive holding the rug in place to break down.
What are the steps to repair a cracked concrete subfloor?
Use a hammer and cold chisel to remove jagged edges along shrinkage cracks. Remove all dust and debris from the damage by vacuuming. Apply duct tape along both sides of the damage, and fill in the crack with epoxy resin.