Dampness, humidity, and condensation in an RV may lead to mold and mildew, which can quickly take over the RV and make it uninhabitable. Unless they are parked in a very dry climate, most RVers would benefit from some suggestions on how to reduce the dampness, humidity, and condensation that is threatening their RV.


While all window types are subject to condensation, single pane windows are especially prone to it. Condensation occurs when the inside of the window is warm while the outside is cold. An easy way to insulate windows is to add window film. The shrinking type of film is applied seasonally and then removed, but there are also more permanent films which can not only improve the energy efficiency of the window, but also add privacy.

A window or roof hatch should also be left open a crack for ventilation and to maintain air quality.


Dehumidifiers are very efficient at removing excess moisture from the air. There are many sizes available, so there is one for any type of RV. If power consumption and/or noise are a concern, there are non-electric dehumidifers, such as Dri-Z-Air, which use pellets to trap moisture and then accumulate it in a basin that needs to be emptied. Such dehumidifiers can be left in the dampest areas of the RV, such as the shower and the overcab loft in a class C motorhome. It is a good idea to leave a few in an RV that is being stored.


Propane releases water vapor into the air, so electric heat is more conducive to keeping an RV dry. Electric conduction heaters are quiet and effective at taking the dampness out of the air. Propane heating should not be completely eliminated, however, since the furnace ducting reaches and heats areas under the RV that would otherwise not be heated.

Exhaust Fans

The range fan and bathroom fans should always be run when cooking and showering to vent moisture to the outside.


It is a good habit to squeegee and then wipe down the shower after using it. A microfiber cloth will trap the water and clean the shower at the same time.

Keeping Fabric Away From Outside Walls

Fabric against an outside wall will cause condensation that will lead to mold and mildew. A vigilant eye must be kept on not only the clothing in the wardrobe and cabinets, but also the mattress if it rests along an outside wall. If there is not a lot of insulation under the bed platform, condensation can accumulate under the mattress as well. In such a case, elevating the mattress onto slats would allow air to circulate underneath.

By combining the above suggestions, it is possible to significantly reduce the dampness, humidity, and condensation in an RV. Doing so will improve the air quality in the unit as there will be less risk of contracting mold or mildew issues.