Moisture movement, according to the second law of thermodynamics, occurs from:

Moisture movement in the context of the second law of thermodynamics is understood as the transition of water vapor from areas of higher moisture content (wet) to areas of lower moisture content (dry). This principle is grounded in the observation that systems tend to move towards equilibrium, where energy, including moisture, balances out over time.

In practical terms, when there is a difference in vapor pressure due to varying moisture levels within a structure or between the inside and outside environments, moisture will naturally migrate from regions where its concentration is high (wet areas) to regions where it is low (dry areas). This movement is driven by the need to equalize moisture levels, which aligns with the thermodynamic principle that systems will evolve toward states of maximum entropy or disorder, favoring a more uniform distribution of moisture.

Understanding this concept is vital for building analysts, especially when evaluating indoor air quality, designing effective moisture control systems, or assessing potential problems related to mold growth or structural deterioration due to excessive moisture accumulation.