Water Loss Class 1:

Slow Rate of Evaporation Water losses that affect only part of a room with low-permeance/porosity materials (e.g. plywood, particle board, structural wood, VCT, concrete).  Little or no wet carpet and/or cushion is present (or damage confined to a small area, or wet for a short period). Minimum moisture is absorbed by materials, which release that moisture slowly.

Water Loss Class 2:

Fast Rate of Evaporation 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 structural materials (e.g. plywood, particle board, structural wood, VCT, concrete).

Water Loss Class 3:

Fastest Rate of Evaporation Water may have come from overhead. Ceilings, walls, insulation, carpet, cushion, and subfloor in virtually the entire area are saturated.

Water Loss Class 4:

Specialty Drying Situations

These losses involve wet materials with very low permeance/porosity (e.g. hardwoods, subfloors, plaster, brick, concrete, stone, crawlspaces). Typically, these are deep pockets of saturation, which normally require very low specific humidity.