There are few catastrophes that can cause more damage to a house as frozen pipes. Frozen pipes are prone to bursting due to the expansion of water when it freezes. If the expansion is sufficient, the pipes will begin to crack. The cracks may be very small, and not noticeable, but they will be sufficient to let the pipe leak after the ice has melted.
For these reasons, it is important to prevent any freezing that may occur in the first place. Every homeowner should know how to prevent frozen pipes in a crawlspace, as it is a particularly vulnerable area.