Niiskuskoormus

Niiskuskoormus is a term used in material science and building physics to describe the moisture-related load that a material, component or structure must tolerate. It results from environmental humidity, precipitation, condensation and liquid water ingress, as well as the sorption and desorption of moisture by hygroscopic materials. In practice, niiskuskoormus is quantified by measures such as moisture content, relative humidity exposure, or moisture flux across boundaries.

Moisture content (MC) expresses how much water a material contains relative to its dry mass, typically given as percent or kilograms of water per kilogram of dry material. Equilibrium moisture content (EMC) represents the moisture content at a given temperature and humidity where the material is in balance with its surroundings. Moisture flux describes the rate of moisture transfer through a boundary.

Moisture loading can cause a range of effects: wood may swell or warp; metals may corrode; insulation performance can decline; and mold or fungal growth may appear if conditions remain above thresholds. In electronics and textiles, absorbed moisture can alter dielectric properties and dimensional stability, influencing reliability and fit.

Design and maintenance strategies mitigate niiskuskoormus by considering expected climate, selecting moisture-tolerant materials, applying vapour barriers, controlling air humidity, and ensuring proper drainage and ventilation. Dew point and condensation risk analyses, as well as moisture monitoring, help keep exposures within acceptable limits.

Niiskuskoormus is related to related concepts such as moisture content, relative humidity, sorption isotherms, and diffusion. It is encountered in standards and guidelines for building physics, wood technology, and materials engineering in Estonian-language resources and broader European practice.