As you may know, when materials are put under heat, they tend to expand. The opposite is true when materials are put in cold conditions. While expanding and contracting can be rough on a material, it won’t immediately result in issues. However, if this expanding and contracting is done in a relatively short span of time, it can cause some serious damage.
A perfect example of this would be putting cold liquid in a hot glass. Imagine your dishwasher just finished its heated drying cycle. Feeling a little thirsty, you grab a glass from the dishwasher and pour ice cold water in it. As soon as the cold liquid hits the glass, heat is quickly taken away from the glass and it rapidly contracts. The sudden shift in temperature causes the glass to form multiple cracks and shatter.
This is thermal shock, and it’s something that affects all kinds of substances. While wood, metal, and other roofing materials aren’t as brittle as glass, thermal shock can create cracks and other trauma for them. If those cracks lead to leaks, you could have a big problem on your hands.