What are the IICRC water damage classes 1, 2, 3, and 4?
The IICRC S500 standard classifies water damage into four levels (Classes 1 through 4) based on how much moisture materials have absorbed and how quickly that moisture can evaporate, independent of water contamination category.
Water damage severity in the IICRC S500 standard is measured by four classes that reflect the amount of moisture absorbed by building materials and the rate at which that moisture will evaporate. The team 1 involves the least water absorption, typically affecting small areas with dry materials like gypsum wallboard or carpet in one room. The team 2 extends to larger areas and includes materials with higher water retention, such as insulation, concrete, or hardwood subfloors. The team 3 represents widespread saturation in three or more rooms or floor-to-ceiling situations where water affects structural cavities and concealed spaces. The team 4 describes moisture deep in dense materials like brick, concrete slabs, hardwood, or plywood that dry very slowly and require specialized drying techniques.
These classes are distinct from water categories, which define contamination level (clean, gray, or black water). A single water event can be clean the team 3 water or contaminated the team 2 water. Restoration professionals use the class rating to determine drying time, equipment needs, and whether structural drying and dehumidification strategies must be intensified. The team 1 and 2 losses typically dry within days to one week, while the team 3 and 4 may take weeks and demand aggressive airflow, dehumidification, and monitoring to prevent mold and secondary damage.