Lesson 4.2.2
Class 1 to Class 4
Class 1
Minimal absorption / evaporation load
Under 5%
Wet porous materials affect less than 5% of the combined floor, wall and ceiling surface area in the space. Low-evaporation materials and assemblies have minimal moisture absorbed.
Class 2
Significant absorption / evaporation load
5–40%
Wet porous materials affect roughly 5% to 40% of the combined floor, wall and ceiling surface area. Low-evaporation materials and assemblies have minimal moisture absorbed.
Class 3
High absorption / evaporation load
Over 40%
Wet porous materials affect more than 40% of the combined floor, wall and ceiling surface area. Low-evaporation materials and assemblies have minimal moisture.
Class 4
Bound or deeply held water
Specialised dry
Significant moisture absorption into low-evaporation materials and assemblies. Requires specialised drying methods, extended drying time and vapour pressure control.