Humidity and moisture control is a concept truly understood by few people. For the most part, human beings are most comfortable between 40% and 60% relative humidity. In winter’s colder temperatures, percent relative humidity can fall well below 40%. Warm summer months can push it far above 60%.
When trying to control humidity in a building, it’s important to realize that humidity typically rises and falls in response to current outdoor conditions. Moisture vapor passes through walls fairly easily unless a wall is equipped with a non-permeable vapor barrier. Leaking window frames, poorly insulated walls and other untended openings in the building structure can allow moisture to invade living spaces. However, you can minimize the effects of outdoor influences by providing a vapor barrier in the building’s walls and ceilings.
Another opportunity to get indoor humidity under control is to assess and correct wet basement walls and eliminate any standing water. Relative humidity is inversely proportional to temperature in a closed space. For example, say you have a closed room that contains a certain amount of moisture. When the temperature rises, the percent relative humidity will fall. When that same room is cooled, the percent humidity will rise. During a hot and humid summer, air conditioning will remove some unwanted moisture while cooling an indoor space – all the while raising the percent relative humidity in the home or building.
By being aware of some of these concepts, you can more easily identify ways to balance the effects of moisture and humidity and maintain an ideal indoor environment for your needs.