By Barry Stone
Dear Barry,
With the winter months fast approaching, I wish to inquire about a condition inside our home. Each morning the inside casement windows are covered with heavy moisture. What is the cause of this and what can be done to remedy it? Our thermostat is generally set at 65 degrees at night. Needless to say, the moisture ruins the paint and causes the frames to rust.
- Betty
Dear Betty,
Moisture condensation on the interior surfaces of windows is a common occurrence in many homes, resulting when high humidity makes contact with cold window surfaces. The most common source of humid air within a home is wetness in the soil below the building. As ground water evaporates, vent openings in the perimeter foundation usually provide a means of escape to the exterior atmosphere. When insufficient ventilation is provided, this vapor can migrate through the floor and into the dwelling. Therefore, your first step should be to check the outside of your home for vent openings.
The subarea should be cross ventilated -- that is, vents should be installed on opposing sides of the building, and there should be at least one square foot of total vent openings for each 150 square feet of floor space. If ventilation is adequate, and condensation still occurs, then a plastic membrane (commonly known as visqueen) should be spread over the ground beneath the building. This will restrain evaporation of ground water.
If, however, your home is built on a concrete slab foundation, then ground moisture may be evaporating through the slab. In this case, special sealants can be applied, but this would entail temporary removal of the carpets.
Finally, if all else fails, you can install dehumidifiers in your home to reduce the amount of moisture in the air.
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