What are the different Classes of Water Damage Common in Philadelphia?
Elite Water Damage and Fire Restoration 

From Wikipedia, the free encyclopedia....

Class of water damage is determined by the probable rate of evaporation based on the type of materials affected, or wet, in the room or space that was flooded. Determining the Class of Water is an important first step, and will determine the amount and type of equipment utilized to dry-down the structure:

Class 1 - Slow Rate of Evaporation. Affects only a portion of a room. Materials have a low permeance/porosity. Minimum moisture is absorbed by the materials.

Class 2 - Fast Rate of Evaporation. Water affects the entire room of carpet and cushion. May have wicked up the walls, but not more than 24 inches.

Class 3 - Fastest Rate of Evaporation. Water generally comes from overhead, affecting the entire area; walls, ceilings, insulation, carpet, cushion, etc.

Class 4 - Specialty Drying Situations. Involves materials with a very low permeance/porosity, such as hardwood floors, concrete, crawlspaces, plaster, etc. Drying generally requires very low specific humidity to accomplish drying.