What does vapor diffusion refer to?

Vapor diffusion specifically describes the process by which water vapor moves through a solid material, such as walls, ceilings, or floors. This occurs due to differences in vapor pressure across the material, leading to moisture movement from areas of higher vapor pressure to areas of lower vapor pressure. It is a critical concept in building science because understanding vapor diffusion helps in managing indoor air quality, moisture control, and overall building performance. Properly managing vapor diffusion can prevent issues like condensation, mold growth, and deterioration of building materials, making it essential for effective building design and energy efficiency.