Dampfdichten

Dampfdichten refers to the ability of a material or construction element to resist the passage of water vapor. This property is crucial in building construction to manage moisture and prevent associated problems such as mold growth, material degradation, and reduced insulation effectiveness. Materials with high dampfdichten are often called vapor barriers or vapor retarders, depending on their specific permeability rating.

The movement of water vapor through building components occurs due to differences in vapor pressure, which are influenced by temperature and humidity. In cold climates, warm, moist indoor air tends to move outward through the building envelope, where it can condense on colder surfaces, potentially causing damage. In warm, humid climates, the direction of vapor drive can be reversed.

Dampfdichten is quantified using a permeance value, typically measured in perms (US) or nanograms per second per square meter per pascal (ng/(s·m²·Pa)). Materials are categorized based on their permeance: vapor impermeable (less than 1 perm), vapor semi-impermeable (1-10 perms), and vapor permeable (greater than 10 perms).

In construction, the application of dampfdichten materials is carefully considered as part of a holistic building science approach. A vapor barrier is usually placed on the warm side of the insulation in cold climates to prevent interior moisture from reaching cold surfaces. Conversely, in hot, humid climates, the vapor retarder might be placed on the exterior side of the insulation. Proper installation and sealing are essential to ensure the effectiveness of dampfdichten layers.