High humidity in the home can cause more than discomfort, as excessive moisture can cause mold and mildew growth. When combined with warm temperatures, this can also allow dust mites to thrive. The causes of high relative humidity (RH) levels are varied. Showers, clothes dryers, steam from cooking and splashing from tubs and sinks are common causes of increased humidity. Plumbing leaks, poor ventilation and other structural and systemic issues are also likely culprits. If not addressed, excessive moisture can lead to odors, wood rot, damage to painted surfaces and even structural damage.
To determine if a home has elevated RH, first measure it using a hygrometer, which is readily available at hardware stores. According to the U.S. Environmental Protection Agency, keeping indoor humidity below 50% is best for warmer months, while levels as low as 30% are acceptable during colder weather. Take measurements in various parts of the home to determine if high RH is localized to certain rooms or areas such as the basement or attic, or if the levels are elevated throughout the home.
Using exhaust fans to ventilate bathrooms, laundry rooms and kitchens can reduce RH. Fans should be installed to vent to the outdoors. Odors and pollutants will be removed along with the moisture. Exhaust fans should be used to rid the room of moisture-laden air, and limit condensation on walls, ceilings and other surfaces.
Portable dehumidifiers can be used effectively in locally damp spaces such as a basement. Dehumidifiers work best at minimum temperatures of 65°F/18°C. If the space is cooler than this, the unit may ice up, but some models have an automatic shutoff function. The manufacturer will state the square footage appropriate for each model. A unit with insufficient capacity will not reduce humidity to desired levels and will waste energy.
Find and fix local sources of excessive moisture, such as a leak in a basement. When the source of moisture is eliminated, RH in that area should fall. Be sure that clothes dryers vent outdoors, and check the hose leading from the dryer to the exterior vent to make sure it is clear of lint and other debris.
Controlling household humidity can add to the comfort and well-being of the people who live there and the home itself.
This article was provided by Pillar To Post Home Inspectors. For more information, go to pillartopost.com.
