What Is Class 4 Water Damage?

According to the IICRC, a class 4 water damage is where water intrudes and is trapped by building materials and assemblies, which makes the restoration process complicated, time-consuming, and expensive. Affected areas are highly porous or tightly confined and require unique methods and equipment, longer drying time, or substantial vapor pressure differentials. An example would be a severe sewage backup that permeates floor and wall systems.