Monday, February 6, 2023


RV moisture misery

By Chris Dougherty
Chris Dougherty is a certified RV technician. Here is a letter he received from a reader while he was serving as’s technical editor.

Dear Chris,
Condensation forms inside both the wardrobe and the cabinets on my slide-outs only, not in any other storage compartment in my travel trailer when the temperature gets down to the lower 40s. Why is this and what can I do about it? —Todd

Dear Todd,
What you’re experiencing is quite normal for a minimally insulated coach. My first full-timing coach was an old Southwind and it did the same thing. In fact, there were icicles forming on the walls in closets with no leaks … all from condensation.

Because RVs are such small spaces, humidity levels tend to be really high. Showering, washing dishes and even breathing all contribute. Even if the main part of the coach is heated and the air vented or exchanged, closed off areas under cabinets and in closets, etc., can collect the moisture and cause the condensation.

First thing would be leave the cabinets and closets open so more air can circulate within. Next, ventilate the coach well on a dry day. I used an electric dehumidifier to dry out the inside of the coach, and you’d be amazed at the amount of water it took out. There are chemical dehumidifiers on the market, as well as some other little air dryers, but as I have not tested them I can’t speak to their effectiveness.

##RVT772 ##RVDT1259


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3 years ago

I’m convinced that you need a “real” dehumidifier. As mentioned above, there is a lot of humidity inside an RV of any type. Running the dehumidifier when you are away or at night (in the bathroom with the door shut to dry it out and dry towels, etc) will make a world of difference. Anything that does not actually remove humidity is useless.
Perhaps in the west there are “dry days”. Here in the Midwest there are wet days and damp days. Need a dehumidifier all year long.

Donald N Wright
3 years ago

Does cat litter work as a cheap dehumidifier ?

3 years ago

??? I do not see how… unless it is used to pick up a floor spill :-/

Cliff. Devine
6 years ago

Dear Chris,

I have had several types of RV’s. And in all of them I have used Dri-Z-Air, to control moisture. Plus when RV is in storage, Leave cabinet doors open. I have not had any condensation problems. Also do run a small heater, on low setting. Just to keep the temp above freezing.

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