How can I determine the level of moisture in my home?

John P. Lapotaire, CIEC

Weather forecasters talk about the relative humidity outdoors. Likewise, the inside of your home has a relative humidity, which is a measure of the moisture content in the air. Hardware stores sell instruments to measure the humidity inside your home.

Humidity is an important factor affecting the comfort level in your home. Have you ever awakened in the middle of a winter night to discover that your throat and nose feel very dry? That could mean the humidity in your home is too low. To remedy the problem, some people use humidifiers, which are designed to raise the humidity in a home. Your goal should be to have enough humidity in the air so the members of your household can stay healthy and comfortable.

Too much humidity can cause droplets of water to form on your walls, floors and windows, which can lead to mold growth. This formation of water droplets is called condensation. It occurs when warm moisture comes in contact with a cool surface. If you pour a glass of ice water and leave it on your kitchen table, the glass soon will begin to sweat. The sweating does not come from inside the glass. It is created when moisture from the air condenses when it comes in contact with the cold outer surface of the glass.

A sign of excessive humidity in a home can be condensation on the inside of windows, especially if you have double- or triple-pane windows. If condensation is present for prolonged periods, take steps to reduce the level of moisture or increase ventilation in your home. Condensation also can result from the use of unvented fuel-burning appliances, such as kerosene heaters or wood-burning stoves. If you use such appliances, have them inspected by a professional contractor or a utility company representative.

Another sign of excess moisture could be the warping of floors or difficulty in opening wood windows and doors. In such cases, the moisture from the air is absorbed into the wood, causing it to expand.