High humidity in the home can cause more than discomfort. Excessive moisture can promote mold and mildew growth, and when combined with warm temperatures can also allow dust mites to thrive. The causes of high relative humidity (RH) levels are varied. Showers, clothes dryers, steam from cooking, splashing from tubs and sinks, and other activities can increase 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, problems with painted surfaces, and even structural damage.

The first step in determining if a home has elevated RH is to measure it using a hygrometer, which is readily available in hardware stores. According to the US Environmental Protection Agency, keeping indoor humidity below 50% is best for warmer months, while levels as low as 30% are acceptable during colder weather. Measurements should be taken 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 is a very effective way to reduce RH. Exhaust fans should be used regularly and must be installed so that they vent to the outside. Another benefit is that odors and pollutants will be ventilated along with the moisture. Many newer exhaust fans are both extremely quiet and efficient. Exhaust fans should always be used especially after showering to not only rid the room of moisture-laden air, but to discourage 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; some models have an automatic shutoff functions should this occur. The manufacturer will indicate the square footage appropriate for various models. A unit with insufficient capacity for a particular space will not effectively reduce humidity to desired levels and wastes energy, too.

Find and fix any local sources of excessive moisture. A leak in a basement or crawlspace wall can significantly raise humidity levels and should be addressed. Once the source of moisture is eliminated, RH in that area should fall. Be sure that clothes dryers vent to the outside at all times, and check the hose leading from the dryer to the vent to make sure it is clear of lint and other debris.

Questions? Comments? Looking to buy or sell a house in Miami or Sarasota, Florida? Contact Kijner & Sons International Realty at info@kijner.com

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Source: 25th Edition of CRS Consumer Article (January 15th, 2013) - CRS-Pillar To Post Partnership - Article courtesy of Pillar To Post Professional Home Inspection