Interior Moisture Problems

Interior moisture problems are a relatively new phenomena in temperate climates. Older homes tended to leak air and this air movement helped keep homes dry. The problem was that these older homes were also very expensive to heat and cool. As a result, we started to insulate and tighten homes. A very good idea, but the unintended consequences of such energy saving measures was that some homes experienced moisture buildup and damage.

Sources of Interior Moisture

Moisture in homes comes from a number of sources: roof leaks, wet lots, wet basements and crawl spaces, plumbing leaks and people. People? Yes, that's right, we are among the biggest contributors of interior moisture.

The average individual puts off about 1 quart of moisture per day as a result of respiration and perspiration. We also produce interior moisture when we: cook, wash, clean, water house plants, and have pets. Most of this moisture is absorbed by the interior air of the house. The warmer the interior air, the more moisture it can absorb.

Big homes with fewer inhabitants have lots of air volume to absorb the moisture produced by each individual. Smaller homes with many inhabitants have a much lower volume of air per inhabitant. Properly vented homes, homes with forced air heating systems, and homes in dryer and exposed locations have fewer moisture relatd issues.

Moisture problems are also found in homes that were previously heated by a forced air furnace and those recently insulated and weather stripped. The problems in such homes is usually the result of inadequate or improper workmanship or modifications. The moisture problems may be caused by the following:

  • a decrease in the air movement through the house, e.g. new tight windows, elimination of a chimney.
  • a reduction of paths for the moist interior air to escape to the outside, or

  • a complete exclusion of heat from one part of the house, such as an unused back bedroom.

    These conditions result in relatively high interior moisture levels and some cold interior surfaces where water vapor can condense.

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    Moisture Problems