Undoubtedly, slab foundations have their strengths and weaknesses. But, they often tend to be very popular, particularly in warm climates.
In cold climates, however, property owners prefer a different kind of foundation. This is because slab foundations tend to crack in colder parts of the country which experience freezing weather.
When choosing a particular kind of foundation, it pays to consider the weather conditions and geography. It’s also important to learn about the various solutions available when problems arise due to weather.
Generally speaking, most of the problems that affect slab foundations have to do with shifting soil. When soil beneath the structure shifts, it causes the foundation to move, leading to damage.
This is a typical problem in Dallas, TX. Luckily, many of the problems associated with shifting soils can easily be remedied by a qualified foundation repair company.
Slab foundation is commonly referred to as “slab on grade” foundation. “Slab on grade” foundations are built using a thick slab of concrete and became popular in the 50’s. Even today, they continue to be popular for various reasons as we shall see later.
What Is a Slab Foundation?
Usually, a concrete slab foundation is 4 to 6 inches thick. For strength purposes, the edges of the slab are thicker than other parts. Typically, they are as thick as 24 to 36 inches, and up to 18 inches wide These are called beams. To further aid in strengthening the foundation, the present building practice is to have beams every 8 to 10 feet both in the x and y-direction under the slab.
Steel rods (rebar) or post-tension cables are used to make the poured concrete slab sturdy, more flexible, and capable of bearing the load of the structure.
On site, the concrete slabs foundation is generally poured on a layer of sand. This acts as a padding and helps to improve the drainage conditions.
Houses sitting on concrete slab do not have a basement. Crawlspaces/basements are usually found up North, where the average climate is colder. A reason for this is because up North, the terrain tends to have a lot less surface moisture.
Down South, the water table tends to be much closer to the surface. When the water table is within 10 feet from the surface, constructing a crawlspace is equivalent to constructing a well in your basement.
The water will do either of two things: cause your home to float or cause water to seep into the basement of your home. As any construction specialist probably knows, neither option is advantageous to your home’s longevity.
Another reason why concrete slabs are commonly used in areas like Dallas, Texas is because of the soil type. In North Texas, the soil is expansive. It shifts depending on the prevailing weather conditions.
When it’s wet, the expansive clay ground absorbs water and expands. Over time, this may cause your foundation to heave. When this occurs, your foundation will move in an upward direction, causing your it to fail. You may begin to notice cracks in it as well as in your walls.
When it’s dry, expansive clay loses water and shrinks. With time, this causes settlement. Foundation settlement is when there is a downward movement of a building structure, causing it to sink below its original position.
Differential settling can occur, you may begin to notice that one part of your home is lower than other parts. One common sign of differential foundation settling is uneven floors.
Concrete foundation problems are common in properties that have been graded.
Why so?
Because notoriously poor ground soil compaction is associated with grading. When the ground is poorly compacted, the foundation may sink or settle into the ground.
Pros of a Slab Foundation
1. It allows for a wider range of flooring options. Such options include scored or stained concrete as well as a variety of wood products.
2. With concrete slab foundations, mold and mildew are not an issue, neither are insects or rodents. That is because there isn’t space for rodents to nest or mold to form.
3. Slab foundations are generally associated with lower heating and cooling costs. This is essentially because there is no basement beneath them.
4. Building a concrete slab foundation is quicker. In fact, the slab itself is poured in one day. Obviously, preparation is done beforehand. But generally, without weather problems, the entire process usually takes around 4 days.
5. Another advantage of having a concrete slab foundation is that it’s generally less expensive to build. Concrete slab foundations don’t require floor joists, as required with pier and beam structures. For this reason, this cost is eliminated.
Cons of a Slab Foundation
1. Since the slab is made of concrete, cracks can be an issue.
Cracking often occurs due to varying weather conditions and moisture levels. Cracks on interior and exterior walls can also cause issues of structural integrity. Installing a water control system is often a remedy to these problems.
2. Plumbing leaks are harder to access.
This is because the plumbing systems are done beneath the slab foundation. When these leaks occur, an invasive approach is usually required. Essentially, the process involves beating or hammering the slab heavily to break an access hole into the concrete slab foundation. This can create a large and expensive mess.
3. In addition to this, since plumbing leaks are hard to detect, they can go unnoticed for a longer time.
This may eventually cause your foundation to fail as a result of it heaving or drop due to its support erosion. One common sign that you may be experiencing a plumbing leak is a high-water bill.
Sewer line leaks are particularly troublesome and are the case of many foundation problems. It may heave or settle due to a sewer line leak.
4. While insects and rodents can’t get direct access beneath your home, they can burrow through the walls.
This often is the case when the siding is wooden and sits on the ground or when soil is as high as the brick/foundation line. The brick line should be two inches above the dirt.
There you have it, pros and cons of concrete slab foundations. As foundation repair specialists in Dallas, Texas, we know that the foundation on which your home is built has a serious impact on your home’s longevity.
If your home has foundation settling or slab fractures, call us today!