Soil pressure to crack concrete foundation

Is soil pressure enough to crack concrete foundations?

Okay here goes; this is really quite simple.

• The foundation of your house is a stationary object.
• In structural terms, most residential homes have a light foundation.
• Part of the foundation is in touch with the soil.
• The soil moves quite a bit.
• Light foundations on moving or expansive soils are going to move.
• The moving soil puts stress on the stationary foundation.
• Remember something that is stationary will remain stationary until it forcibly moved.
• So the moving soil pushes on the unmoving foundation until the foundation cracks.

WHY DOES THE SOIL MOVE?

Most soil movement is due to what is called expansive soil. When the soil has a high clay content it is called clayey soil. As the clayey soil absorbs the ground water it expands. Think of rice. When you cook rice you start out with 2 cups of rice and 1 cup of water. 20 minutes later you have expanded rice and no water because the rice has absorbed the water and increased in size as a result. As the soil expands it is moving. Expansion is movement. This is known as soil swell.

So when the expansive soil pushes your foundation it is pushing it in. Eventually it stops raining and the sun comes out and the soil dries up. When this happens it is shrinking and moving away from the house. The stress and pressures that the soil caused are now being released. This is know as soil shrinkage.

The wall that was being held in place by the swell will now move back in a time of shrinkage. Think of a rocking motion that happens over a great time. The swell and shrinkage of expansive soil causes foundation movement and failures.

When foundations do crack and fail you should act quickly because the problem will get worse and possibly affect the stability of your home. The soil will continue to move whether you are prepared for it or not.