The recommended humidity level for a home is 35 percent to 45 percent humidity, according to About.com. This offers the best comfort and protects the home from too much moisture or dryness.
There is a range of 10 percent with average humidity levels because the air quality and climate somewhat changes the proper humidity level inside the home. If the humidity is too high, it causes extra moisture in basements and dark corners of the home, which then adds to the risk of mold and structural damage. Having a humidifier in the home helps keep the humidity level at the right percentage. Humidifiers should be placed on the ground a few inches away from a wall.