Moisture Control

Moisture is the primary agent of deterioration in buildings, and hence controlling moisture is crucial to ensuring durability. Moisture is also the most common factor in Indoor Air Quality problems such as mold and odors. The water molecule has many interesting properties that explain its odd behavior and its interaction with materials. Air barriers, vapor barriers, housewraps/WRBs, and capillary breaks are building products and systems whose major function includes moisture control. The required level moisture control, depends on the quantity, phase (liquid, vapor, solid), frequency of the load and the mechanism of movement that must be controlled. The primary sources of moisture: rain and snow, water vapor in the air, ground water, and construction moisture, have different magnitudes and have different significance for different climates, building uses, enclosure types, and materials. Moisture moves by a number of mechanisms: capillary flow, vapor diffusion, air convection, and gravity flow. Each of these mechanisms is driven by different forces and flows at vastly different rates through different materials.

Physics of Moisture Control — by BSC — last modified 2007/04/10

 

Water Vapor Control Basics — by BSC — last modified 2007/04/10

 

Rain penetration control — by BSC — last modified 2007/04/10