What Is Foundation Heave?

In short, foundation heave is the opposite of foundation settlement or subsidence. Foundation heave most often occurs in winter because of the way sudden freezes affect the soil. 

• Snap Freeze 

A sudden freeze is more likely to cause frost heave because it freezes the top layer of soil solid before the frost reaches deeper. As such, when the moisture in lower levels freezes, it has limited space in which to expand. This causes the top layer to push upward as a shelf and put pressure on a property’s foundation and lower flooring. 

Lighter properties are, of course, at higher risk than heavier ones, but the soil under a home has an effect too. Expansive soils that are very absorbent are the most likely to cause frost heave because they have a larger capacity for holding moisture than other soils. The extra weight and force generated by a snap freeze in these soils can be incredibly destructive. 

• Cracking Under Pressure 

When this upward push happens, it puts pressure on a property’s foundation. When a building has a weakness in its foundation, or it is very light, this can cause the floor to heave or bulge upward, cracking the foundation and floor quite seriously. This can be quite subtle at first, but as successive freezes cause the issue to recur, the damage can become quite widespread. 

You will notice bulging and cracking in a floor that has been impacted by frost heave. This will also lead to a sudden increase in dampness and humidity when the cold snap ends and the moisture in the soil starts to thaw. The cracks in your foundation will essentially act as channels into your home for moisture at this point.