Truss Uplift
In homes with manufactured trusses, a seasonal distortion of the truss can occur. This is referred to as truss uplift. Not to be confused with the wind driven lifting that the trusses must be designed to resist, this lifting is due to the seasonal temperature and humidity extremes that cause distortion to the shape of the truss.
Frost Heave Damage to a Foundation
In cold climates it is normal for the soil to freeze in the winter. The depth of the freezing of the soil is called the frost line. The colder the temperature, the deeper the frost line. If the soil is relatively dry, the freezing does not result in much expansion. But if the soil contains more water or has a source of water, there is more expansion. This expansion due to water freezing in the soil is called a frost heave.
A frost heave will damage a foundation. Since the top of the foundation wall is restrained by the wood framing, and by the bottom by the footer, the freezing, expanding soil will push on the exterior of the foundation wall with enough force to crack the concrete.
Is That Concrete Bad?
In older homes with exposed foundation walls, or concrete basement floors, we sometimes see chunks of concrete flaking and breaking away (spalling). Typically, we would also see a white, powdery crust called efflorescence.