Moisture Control Options in the Home

Condensation forms on walls and windows when the humid air vapor condenses on a surface that is cold. This happens because the temperature of the surface is below the dew point for the air temperature and humidity in the home. Even homes with relatively low humidity can have a problem based on the amount of wall insulation, the types of windows and how many layers of glazing they have, and the surface temperature of these windows.


The obvious item that should be addressed before anything would be solving water problems. Even very small leaks can add a great amount of moisture to the home. Be sure to completely seal all leaks prior to attempting other methods of reducing moisture. Aside from the obvious, this includes sealing basement walls and making sure that the soil is properly drained from around the foundation.


One way to reduce humidity is to reduce the generation of water vapor. Some of the heaviest contributors of vapor are clothes dryers vented indoors as an energy saver, cord wood stored indoors, unvented kerosene heaters used indoors, large numbers of house plants, stove top cooking in open containers, and extended showers or baths. Also, if your home is built over a crawl space, moisture may be evaporating from the soil and entering your home. Covering the floor of the crawlspace with a moisture resistant material such as 6 mil. plastic will help.


Inside humidity levels can be reduced by using a dehumidifier. This can be an expensive option as they can consume an amount of energy equivalent to a 15 cubic foot freezer. Also, most models are designed to operate at humidity levels above 50%. This level may be too high to solve moisture problems in many homes. If your humidity is above 50% and ventilation is not feasible, the use of a dehumidifier would be a good but expensive option.


Increasing the ventilation in a “tight” home can be very effective. This includes the constant use of ducted ventilation fans such as a bath fan. They should be run 20 minutes after showers and 30 minutes following cooking or dishwashing. You may consider having a dehumidistat control installed to operate the exhaust fan or wire the fan to the light switch so that it is activated when the switch is turned on. Be patient with this option as it takes time to work. A wood structure with wood trim can store large amounts of water.


Other methods include the installation of an air to air exchanger and warming up surfaces that condensate. Adding a layer of glazing on single or double glazed windows will reduce window condensation a great deal. Adding plastic to the window will also achieve a desirable effect unless humidity levels in the home increase and outside temperatures decrease significantly. Finally, raising the temperature and increasing wall insulation will warm up the surfaces of walls and ceilings reducing the chance that the temperature of those surfaces will be below the dew point of the homes air.


If all else fails and your stuck with wiping off moisture on windows and wood work, use a dilute bleach solution as a final cleanser after the surface has dried. One cup of bleach to one gallon of water should be enough. Wash the wood or drywall surfaces with this solution and let it dry. Avoid using cleaning solutions that contain phosphate, since they can leave a residue that provides food for the mold. If the mold has taken hold in the wood fibers, it may be necessary to use a sealer type paint once the wood has completely dried out. Drywall material that has become infested with mold growth will always support mold growth. The use of a sealer is only a short term fix. The only way to truly eliminate the problem is to reduce the moisture problem and replace the effected drywall.


If you need any more information or require the services of an indoor air specialist to identify specific sources of moisture and give you solutions to specifically meet your needs, contact your local health department for a list of providers.


For more information on mold, visit my link to frequently asked questions regarding mold at http://www.environmentalhealthguy.com/faq_category.php?catID=31


Christopher A. Hinz
Environmental Health Specialist
Waushara, Green Lake, and Marquette Counties.