Dew point temperature

Dew point is the temperature at which air becomes saturated with moisture vapor, and can hold no more water vapor. When air is cooled, its capacity for water vapor is reduced. Eventually, if temperature is cooled enough, the relative humidity will reach 100%, or saturation. When this occurs, the air has reached its dew point temperature.

Calculating the dew point temperature is especially important when monitoring humid air masses. Typically, the most humid air mass in a structure affected by water intrusion will be the indoor air. Restorers then compare the Dew point to surface temperatures throughout the structure. If surfaces are cooler than the dew point of the surrounding air, water will condense on those surfaces and possibly cause secondary damage.

Note: Secondary damage can occur even if condensation does not. High humidity alone can result in secondary damage.