Interstitial condensation

Interstitial condensation is a form of structural damping that occurs when warm, moist air penetrates inside a wall, roof or floor structure, reaches the dew point and condenses into liquid water. Interstitial condensation is differentiated from surface condensation in buildings sometimes called "cold-bridge condensation" or "warm front condensation" where the condensation forms on the interior or exterior surfaces of a building rather than inside the wall or roof cavities. The warm, damp air may penetrate a wall from the inside of a heated building in a cold climate or from the exterior of an air-conditioned building in a warm climate. This condensation may allow mold growth, rotting of timber, corrosion of metal components and/or a reduction in the thermal insulation's effectiveness. The resulting structural damage may occur without visible indications until significant damage has occurred. Most building materials are permeable so the common method of controlling interstitial condensation is to control indoor moisture at its sources or through dehumidification and/or ventilation and add an impermeable barrier on the warm side of the wall.