Humidity control in tent trailer

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Jul 4, 2006

Have a hybrid. Tents out, sleeping well. Wake up and the ceiling inside of the tents only are covered with moisture [like heavy dew]. Assuming it is from breathing all night because the rest of the camper is fine and dry. my wife's and my side is heavier moidture than the side where my daughter sleeps. Our's is heavy and daughter's is very light. Even had ac on one night and still woke up with it. had a fan clipped on to overhead tent pole to circulate air and still had it. it's bad enough that when you wake up in the a.m. you can tap the top of the tent and get a instant second long rainshower in your bed.
I do not want to have to run a dehumidifier in the camper. don't want to have to buy one and it'll just take up more space.
have thought about spraying inside of tent with silicone waterproof spray but figured that wouldn't solve problem. the moisture isn't coming through from the outside, it's only on the inside.

need a miracle solution. help here please, at wit's end !!!!!!!

John From Detroit

Well-known member
Apr 12, 2005
Davison Michigan
Well, I can tell you that a de-humidifier won't help much as the Air Conditioner duplicates that function

Using Scotchguard won't likely help but may help with other stuff.  Fresh air may help depending on the outside air conditions, but mostly I can't think of a solution


Moderator Emeritus
Mar 3, 2005
Elkhart Lake, WI for the summer. Work at Road Amer
Miracle solution - Stop breathing! ;D ;D ;D

Seriously, most older tents had little flaps near the top that you could open to let the warm, moist air out. Modern tents are made of a breathable fabric. You should be able to sew in a vent flap with little trouble. The other walls of the camper are more or less insulated, and you don't get that 'moisture on the outside of a cold glass' effect because they stay relatively warm.

Gary RV_Wizard

Site Team
Feb 2, 2005
West Palm Beach, FL
Your breathe contains a lot of moisture and the relative humidity inside the trailer climbs all night when it is closed up. The humidity condenses on cool surfaces. I'm guessing that the fabric is the least insulated place and thus where the temperaure is closest to the cooler outside air. That means condensation will form there first and most. 

The a/c shoud solve the problme if it runs often enough, since it will dehumidify. But if it is cool outside the a/c compressor may not cycle enough to remove much moisture. You may have to turn the a/c temp down quite low to make it effective as a dehumidfier. 

Circulating the air inside with a fan doesn't help much, but exchanging the inside air with outside air will. Open a window or flap near each bed to let the moisture escape. Use a window fan if need be.

Carl L

Moderator Emeritus
Mar 14, 2005
west Los Angeles
What is happening is that you are in tent.  The moisture in your tent produced by you all breathing and perspiring during the night migrates upward to the cloth of the tent.  It passes thru the cloth at which point it is exposed to the sky.  The night sky at altitude and in dry climates has a radient temperature of 3?C above absolute zero.  Now that is waay cold.  The water vapor condenses and soaks into the cloth and causes even more water vapor to condense, etc. etc..

Tent campers cure this with a rain fly suspended above the wall cloth of the tent.  It insulates the tent from the cold black of space and the water vapor can escape.  Course this does not help you in a tent trailer, tho you might try using a cheap nylon tarp but that seems to me a bit much trouble.  A better sceme is just find a campsite that offers you at least partial overhead shade.  It should have the same effect.

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