In addition to high levels of moisture in new building assemblies (e.g. concrete, lumber), we can find:

• Inside sources (vaporized moisture)
  
  • Occupants: four people add about 5 litres/day
  • Activities such as washing, cleaning and cooking can add another 4-5 litres/day
  • Plants and pets contribute 4-5 litres/day
  • Use of humidifiers
  • Dryer exhaust duct (ensure proper sealing and operation of vents)
• Outside sources (bulk moisture)
  
  • Ice, snow, rain, fog, high humidity and surface run-off
  • Ground water in the soil

Water has three phases: solid, liquid and gas/vapour. Of its three phases, liquid and vapour (when it condenses) are the most invasive and destructive elements to a building