Just as moisture collects outside of a glass of cold water during humid weather, moisture can condense on the inside of surfaces of the RV during cold weather when relative humidity of the interior air is high. This condition is increased becuase the insulated walls of a RV are much thinner than house walls. Estimates indicate a family of four can vaporize up to three gallons of water daily through breathing, cooking, bathing and washing.

Unless the water vapor is carried outside by ventilation, or cendensed by a dehumidifier, it will condense on the inside of windows and walls as moisture, or in cold weather as frost or ice. It may also condense out of sight within the walls or the ceiling where it will manifest itself as warped or stained panels. Appearence of these conditions may indicate a serious condenstation problem. When using yoour RV, you should at all times take necessary action to minimize the effects of excessive moisture and condensation.

Tips to Controlling Condensation

To avoid condensation problems, try to follow these tips to help alleviate excess moisture.

  • Allow excess moisture to escape to the outside when bathing, washing dishes, hair drying, laundering and using appliances and non-vented gas burners.
  • Keep the bathroom door closed and roof vent opened (if equipped, exhaust fan on) when bathing/showering and for a period of time after you have finished.
  • When cooking, always operate the range hood fan. Cooking releases heat and moisture that can quickly result in condensation in your RV; operating the range hood fan can be effective in removing both.
  • Do not hang wet clothes in the RV to dry.
  • In hot weather, start the air conditioner early as it removes excess humidity from the air while lowering the temperature.
  • Manage the inside temperature during cold weather. The higher inside temperature along with colder outside temperatures will cause condensation to form on areas that are not insulated as well as others (windows, vents, wall studs, etc.).
  • Use a fan to keep air circulating inside the vehicle so condensation and mildew cannot form in dead air spaces. Allow air to circulate inside closets and cabinets (leave doors partially open) so the temperature inside the cabinets the same as in the rest of the unit. Please keep in mind that a closed cabinet full of stored goods prevents circulation and can cause condensation.

The natural tendency would be to close the RV tightly during cold weather. This will actually compund the problem. Simply put, youo need to get the moisture in the air that is created from normal use outside. The most effective way is utilizing your vents and vent fans.

Where There is Moisture, There May Be Mold

Molds are microscopic organisms that naturally occur in virtually every environment, indoors and out. Outdoors, mold growth is important in the decompostition of plants. Left unchecked, molds break down natural materials such as wood products and fabrics.

Accordng to the Center for Disease Control, exposure to damp and moldy environments may cause a variety of health defects, or none at all. Some people are sensitive to molds. For these people, molds can cause nasal stuffiness, throat irritation, coughing or wheezing, eye irritation or, in some cases, skin irritation. People with mold allergies may have more severe reactions. Immune-compromised people and those with chronic lung illnesses, such as obstructive lung disease, may get serious infections in their lungs when they are exposed to mold.

For mold growth to occur, temperatures must be between 40 degrees and 100 degrees Farenheit, and there must be a source of moisture such as humidity, standing water, damp materials, etc. Indoors, the most rapid growth occurs with warm and humid conditions.

By controlling relative humidity, the growth of mold and mildew can be inhabited. In warm climates, use of the air conditioner will reduce the relative humidity. Vents are located in the bathing and cooking areas and constant use is advised during food preperation and bathing, even during colder weather.

Additionally, opening a window during these activities will assist in ventillation. In extremely humid conditions, the use of a dehumidifier can be helpful. Frequent use of your RV or cleaning reguarly is an important preventative measure. Further, any spills should be wiped up quickly and dried as soon as possible. Avoid leaving damp items lying about.  On safe surfaces, use mold or mildew killing cleaning products. Check sealants regularly, and reseal when necessary to avoid water leaks.

Proper preventative maintanance to the RV and its accessories, as described both in this manual and in accompanying literature, will provide the best protection to the RV.