Water Damage Classes

Class 1 – Slow rate of evaporation

• Small size water loss.
• Water losses that affect only part of a room or area.
• Losses with low-permeance/porosity materials (e.g. plywood, particleboard, structural wood, VCT, concrete).
•  Little or no wet carpet and/or cushion is present.
• Minimum moisture is absorbed by materials, which release that moisture slowly.
• On hot dry days this class is an ideal candidate for open system dehumidification.

Class 2 – Fast rate of evaporation

• Medium size water loss.
• Water losses that affect the entire room of carpet and cushion.
• Water has wicked up walls less than 24 inches.
• There is moisture remaining in the structural materials (e.g. plywood, particleboard, structural wood, VCT, concrete).

Class 3 – Fastest rate of evaporation

• Large size water loss.
• Carpet and pad with water from coming from above or water wicking more than 24” up walls. 
• Ceilings, walls, insulation, carpet, cushion and subfloor in virtually the entire area are saturated.

Class 4 – Specialty drying situations, focus on bound water

• Involves wet materials that are very low permeance/porosity (e.g. hardwoods, subfloors, plaster, brick, concrete, stone, crawlspaces).
• Typically there are deep pockets of saturation that normally require very low specific humidity.
• In laymen's terms a class four water loss involves drying hardwood flooring, concrete or some such material.

To learn more, read about Drying Methods.