Dampness

Dampness refers to the presence of unwanted moisture in or on materials, objects, or spaces, greater than what is typical for the environment. In buildings, dampness most often arises from condensation, rain penetration, rising damp from the ground, or leaks from plumbing or roofing. Persistent dampness can arise when ventilation is inadequate or when insulation is insufficient to separate warm air from cooler surfaces.

Surface signs include staining, wallpaper peeling, efflorescence on masonry, and a musty odor. Inside walls, dampness can lead to mold and mildew growth, which poses health risks and can degrade materials.

Indoor air humidity and surface moisture can be assessed with hygrometers and moisture meters; ideal indoor relative humidity is commonly maintained around 40-60%, depending on climate.

Prevention and remediation: locate and repair leaks; improve ventilation; use dehumidifiers; seal penetration points; install or repair damp-proof courses or membranes; improve insulation; use moisture-resistant building materials; clean mold with appropriate methods.

Unlike humidity, which is a measure of moisture in the air, dampness describes the condition of surfaces or materials that retain excess moisture. In environmental and building science, dampness is analyzed because of its impact on indoor air quality, comfort, and structural integrity.