Life is spawned from one of the simplest compounds on earth, water. Without water life would not exist. Scientist today search for signs of water on Mars, knowing it is the basis for any life to survive. For all of water’s life giving goodness, it’s the enemy of our homes. Too much can make a house virtually uninhabitable.
The majority of house design is focused on keeping water out or away from the structure. A roof to shed the water, drainage to send it away, more drainage around the foundation and water resistant cladding. For all the water repelling measures incorporated into a house, moisture will always be a part of the indoor environment. And that is fine, because a little is good, too much and bad things begin to occur.
At times it seems moisture control and transport are not always well understood or not thoroughly considered during construction. The trend has been for years and continues to be to tighten up houses for better energy efficiency, yet indoor air quality and moisture control are in my experience not given enough consideration.