Why Does Concrete Sink or Crack? | Best Explained

Last Updated on April 15, 2024 by Ryan

Why Slab Foundation Concrete Sinking?

The soil beneath the concrete is the reason of sinking concrete. Concrete is more prone to sinking and cracking if there isn’t adequate soil support for a hefty slab, or if the soil contains a lot of clay. These are some of the most prevalent causes for concrete slabs in Florida to sink.


As previously said, the majority of the soil in our region is Houston black soil, which has a high clay concentration. When wet, this makes it extremely sticky and moldable. When it rains, the clay absorbs as much water as it can and begins to swell. The soil then begins to shrink as it dries out, and it can no longer hold the weight of the heavy concrete on top of it, causing your slabs to sink unevenly.


You may have soil washout if your house was built on sandy soil. When precipitation runs beneath the slab, sandy soil is readily disturbed and washed away. This creates cavities beneath the slab, and the heavy concrete will begin to crack as a result of the lack of appropriate support.


This is a problem that occurs before the concrete is poured. If your concrete was not properly compacted before pouring, the earth beneath it will begin to compress unevenly under the weight of the concrete over time. Sinking and, in certain circumstances, cracks in your concrete will result as a result of this.

Why does concrete crack in Florida?

Most slabs will sink and settle because to the soil conditions in Florida. Concrete slab fractures may develop as a result of this. When the earth under the slab changes and erodes over time, the fractures appear. The slab may fracture under strain if there isn’t enough soil to support it.

Why Concrete Sink Or Crack?

It’s necessary to understand the makeup of the soil that’s trying to sustain the weight of such concrete buildings in order to understand why this happens. While a bag of premix concrete weighs about 80 pounds, concrete used for buildings can weigh up to 150 pounds per cubic foot. Concrete slabs for typical homes (24’x48′) in Tampa, Naples, Orlando, Ft. Myers, and other residential districts can weigh between 5-10 tons when fully cured.

The weight of construction materials, furnishings, and even people is the next factor to consider. The ground beneath your house is attempting to hold anywhere from 15-20 tons, and if the soil is not adequately stabilized, concrete will eventually settle, sinking and cracking. Many homeowners who have spent a substantial amount of money on either building or purchasing a new home may be frustrated by this.

If you’re designing a new house and want to build it in Florida, you’ve come to the right place. To avoid severe sinking and settlement in the near future, call a competent ground improvement firm to analyze your soil and make the required adjustments.

Florida’s soil is unlike that of other states, where water tables and soil composition must be taken into account before building can begin. The state of Florida is covered with more than 1.5 million acres of Myakka sand, which can be seen from almost anywhere. There is also a lot of clay soil, marshes, sinkholes, and water running beneath the earth in Florida.

There are 12 primary “soil types” in the United States, with roughly seven of them found in Florida. In Florida, the most prevalent soils are high in organic matter, acidic, and dark in color. The soil in different cities might differ depending on where you reside.

The soil in Orlando, for example, is highly sandy and clay-based, but the soil in the southern portion of the state is a mixture of sand, clay, and peat moss, with more marshes and bogs.

The seven soil types found across the state of Florida


This is a clay-rich soil that holds moisture well and decomposes fast. It may be found on the east coast, on the southwest, and on the northwest coast.


This is a clay-rich soil that holds moisture well and decomposes fast. It may be found on the east coast, on the southwest, and on the northwest coast.


In southern Florida, it’s primarily found in marshes and swamps. This is a decent agricultural soil, although it may quickly degrade without rainfall.


This type of soil may be found in Florida’s central and east coast areas, as well as in the Everglades. This soil is frequently quite thin, with bedrock visible beneath it.


Most wetlands have them, and they contain dark and organic materials. They can store a lot of water and may be found all across the state. It prefers to live beneath wet meadows rather than in swamps or marshes.


This is a typical sand-based soil found in cities throughout the central, eastern, and western United States, including Orlando, Tampa Bay, Ft. Myers, and Naples, among others.

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