Reference
Plain-language definitions of the water damage, mold, sewage, and structural drying terms our IICRC-certified crews use every day, so you know exactly what is on your estimate and in your report.
The IICRC S500 standard classifies water by how contaminated it is. The category drives what can be cleaned, what must be removed, and how the loss is treated.
Water that originates from a sanitary source and poses no substantial risk to health, such as a broken supply line, a tub or sink overflow with no contaminants, or an appliance water-supply line. Category 1 water can degrade to Category 2 or 3 as it sits, contacts contaminants, or migrates through building materials.
Water that carries significant contamination and can cause discomfort or illness if contacted or consumed. Common sources include discharge from dishwashers or washing machines, toilet overflow containing urine but no feces, and failed sump pumps. Gray water left untreated degrades to Category 3.
Grossly contaminated water that can contain pathogenic, toxigenic, or other harmful agents. Sources include sewage and toilet backflow with feces, seawater, and rising surface water from rivers or streams. Category 3 losses require protective equipment, removal and disposal of porous contaminated materials, and antimicrobial treatment.
While the category describes contamination, the IICRC S500 class describes how much water is present and how hard it will be to dry, which sets the equipment and time needed.
The least amount of water, absorption, and evaporation load. Only part of a room or area is affected, or the wet materials are low-porosity (such as plywood or concrete), so relatively little moisture must be removed.
A large amount of water, absorption, and evaporation load. An entire room is affected, water has wicked less than 24 inches up the walls, and moisture is present in carpet, cushion, and structural materials.
The greatest amount of water, absorption, and evaporation load. Water often comes from overhead, saturating ceilings, walls, insulation, carpet, cushion, and subfloor throughout the space.
Wet materials with very low permeance and porosity, such as hardwood, plaster, brick, concrete, and stone. These deeply held pockets of moisture require longer drying times, low specific humidity, and specialized methods.
Structural drying is governed by psychrometrics. Technicians read the air to manage evaporation and confirm a structure is truly dry, not just dry to the touch.
The study of the physical and thermodynamic properties of air and water-vapor mixtures. In restoration, psychrometry guides drying by tracking temperature, relative humidity, dew point, and vapor pressure to control how fast moisture evaporates from materials.
A measure of absolute humidity: the weight of water vapor, in grains (7,000 grains equal one pound), held in one pound of dry air. Technicians compare the GPP of incoming, inside, and outgoing air to verify that dehumidifiers are actually pulling moisture out of the structure.
The ratio of the water vapor currently in the air to the maximum amount the air could hold at that temperature, expressed as a percentage. Lowering relative humidity speeds evaporation, and keeping indoor RH below about 60 percent helps prevent mold growth.
Removing water vapor from the air to accelerate evaporation and drying. Restoration crews use low-grain refrigerant (LGR) dehumidifiers and, for tough Class 4 losses, desiccant units that adsorb moisture from the air.
When mold or Category 3 water is involved, controlling the air is as important as removing the material, so spores and contaminants do not spread to clean parts of the home.
A filter that captures at least 99.97 percent of airborne particles 0.3 microns in diameter. HEPA filters are used in air scrubbers and vacuums to remove mold spores, soot, and fine debris from the air during remediation.
An EPA-registered product applied to surfaces to kill or inhibit the growth of microorganisms such as bacteria and mold. Antimicrobials are used after extraction and cleaning, not as a substitute for physically removing contaminated material.
Physical barriers, typically polyethylene sheeting with zippered access, that isolate a work area from the rest of the building. Containment keeps mold spores and Category 3 contamination from spreading while affected materials are removed.
A controlled pressure difference, created by exhausting HEPA-filtered air out of the containment area, so air flows into the work area and cannot carry contaminants out. Negative pressure is standard practice for mold and biohazard remediation.
A portable filtration device that draws air through a HEPA filter to remove airborne particles and spores; an optional activated-carbon stage can also capture odors. Air scrubbers clean the air inside containment and can be ducted to create negative air pressure.
Documentation is what proves a loss was handled correctly and keeps an insurance claim moving. These tools turn "it looks dry" into a measured, defensible record.
Documenting the location and level of moisture across a structure using moisture meters and thermal imaging, then recording it daily. Moisture maps guide where to place drying equipment and prove to an adjuster that the structure reached a dry standard.
An instrument that measures the moisture content of building materials. Penetrating (pin) meters read moisture between two probes driven into a material, while non-penetrating (pinless) meters use a sensor pad to read moisture in a zone just below the surface without leaving pin marks. Readings verify drying progress.
Using an infrared camera to detect temperature differences that reveal hidden moisture behind walls, above ceilings, and under floors. Thermal imaging finds saturated areas that a visual inspection would miss, though findings are confirmed with a moisture meter.
A rapid verification method that measures adenosine triphosphate (ATP), a molecule found in living cells, on a surface after cleaning. A low ATP reading confirms that organic residue has been effectively removed, verifying the surface was properly cleaned following a sewage or mold loss.