The Intensity of Water Intrusion

Following a flood, the first order of business for restoration services is to remove the water and residue from the house. After that, they deal with the water that had already seeped its way into the structure. The level of dehumidification necessary depends on how much floodwater the walls and floor have absorbed.

The IICRC S500 standard divides the intensity of water intrusion into four classes:

Class 1

Water intrusion is minimal, often affecting materials with low permeability like plywood, and only needs small-scale dehumidification. In fact, this level of water intrusion is more likely to be related to a leaky pipe or other non-flood causes. 

Class 2

A significant portion of the structure has been inundated and requires a more extensive drying process. The water has seeped between 12 and 24 inches into the structure and into furniture. One major sign of a Class-2 water intrusion is adsorption, where water collects on the surface but doesn't seep into the area.

Class 3

Most of the house has been inundated to beyond 24 inches and requires a major restoration job. In this scenario, even the ceilings have been inundated (possibly as a result of leaks on the roof brought about by constant, heavy rainfall). This type of water intrusion also reaches deep into the subfloor.

Class 4

Soaked materials have gathered enough humidity over time. This requires a concentrated effort to dehumidify the local area.