Humidity levels in a home can have an adverse effect on the house itself, as well as its residents. If levels are too high, mold and mildew can easily grow. If levels are too low, wood may dry out and residents may notice that they have frequent sinus headaches. The key is keeping the humidity within your home at a constant level, somewhere between 20 and 40 percent. In order to gauge this properly, it is necessary to install a few items around the house.
Place a hygrometer in the home. A hygrometer measures the amount of humidity in the air. Models range from low-tech glass bottles with weights inside to high-tech gauges. Hygrometers can be purchased at most home and garden stores or at a hardware store. A simple thermometer with a humidity gauge will also suffice. It should be placed away from direct heat or cold air to get a true reading of the home's humidity levels. Ideally, place the hygrometer in the center of the home.
Install a second hygrometer in your basement. Basements tend to be more humid than the rest of the house. If you have water leakage, the levels may be even higher in the basement. Again, install the hygrometer in the center of the basement away from air.
Wait 24 hours before taking your reading. The hygrometer will need time to adjust to your home's humidity levels to give you a true reading. Outdoor temperatures may also affect the reading. Houses are naturally more humid when it is hot outside and less humid when it is cold.
Correct the humidity level if necessary. If the house is too dry add a humidifier to living areas. If it is only a minor deviation from the recommended amounts, a simple table top humidifier will be sufficient. If the levels are drastically low and residents and pets notice static electricity or periodic bloody noses, consider installing a whole house humidifier. If levels are too high, a dehumidifier should be placed in living areas.
Monitor the humidity levels daily. A small variation does not mean much, but if you notice rapid swings in either direction -- either too low or too high -- you may need to either turn off your humidifier and dehumidifier, or it may simply be due to the weather.