The IICRC WRT body of knowledge explains that to increase therate of evaporation, the surface temperature of wet materials must beabove the dew point temperatureof the surrounding air. When a surface is warmer than the dew point, water molecules have sufficient energy to change from a liquid state to a vapor state and move into the air.
If a surface temperature falls at or below the dew point, condensation occurs instead of evaporation, adding moisture back onto the material. This condition directly opposes drying and can result in secondary damage.
The WRT curriculum therefore emphasizes continuous monitoring of both air dew point and material surface temperatures to ensure evaporation conditions are maintained.
Relative humidity is not a temperature, and vapor pressure equality does not drive evaporation. Only maintaining surface temperatures above dew point ensures positive evaporation potential.
This principle is fundamental to restorative drying and is repeatedly reinforced throughout WRT psychrometric training.

The IICRC WRT body of knowledge requires that restorersrecord and monitor drying measurements at least daily. Daily monitoring ensures that drying systems are functioning properly, drying goals are being approached, and adjustments can be made promptly if progress stalls.
Measurements typically include air temperature, relative humidity, humidity ratio, dew point, and moisture content or moisture levels of affected materials. The WRT manual emphasizes trend analysis-comparing daily readings to confirm consistent moisture reduction.
Infrequent monitoring increases the risk of unnoticed equipment failure, elevated humidity, condensation, or secondary damage. Weekly or bi-weekly monitoring does not meet the professional standard of care outlined in the ANSI/IICRC S500 Standard.
Daily documentation also supports defensibility by demonstrating continuous oversight and proactive management of the drying process. It provides transparency to materially interested parties and ensures accountability throughout the project lifecycle.

The IICRC WRT body of knowledge explains thatlow-grain refrigerant (LGR) dehumidifiersare designed to remove moisture more efficiently at lower humidity ratios than conventional refrigerant dehumidifiers. As a result, LGR units can reduceair vapor pressure to lower levelsthan standard refrigerant systems under similar conditions.
This enhanced capability allows LGR dehumidifiers to continue removing moisture even as the environment becomes drier, supporting faster and more complete drying. The WRT manual highlights this feature as a key advantage of LGR technology in most residential and light commercial drying scenarios.
LGR units do not operate effectively at freezing temperatures, are not optimized for extreme heat, and cannot achieve vapor pressure levels lower than desiccant systems. Desiccants remain superior for very low humidity or low-temperature conditions.
Therefore, the correct benefit under WRT guidance is the ability of LGR dehumidifiers to reduce vapor pressure lower than conventional refrigerant dehumidifiers.