Tuesday, January 5, 2021

Retro Reads: Minimizing Condensation in a Teardrop or Tiny Trailer

Retro Reads: It's winter, it's cold, and I noticed that in the last thirty days an article written almost two years ago still gathered over two hundred page views. Obviously, the information is timely and useful, so I'm republishing an article on condensation and travel trailers--especially tiny trailers, where the space-to-moisture ratio can be a critical factor. I enjoyed researching the article, which includes not just how-to-avoid suggestions but also gets into the science of how you can wake up to wet walls or mattress. 

My first camper was a fiberglass shell mounted on a 1952 Chevy pickup, my college transportation back in the 1970's. I worked summers in a canning factory and always worked up until a day or two before school started. It was seasonal union work, so when I was laid off I had a guaranteed job the next season.

One year I had difficulty with housing and showed up for college at U.C. Davis, California, having only my camper for a home, and I lived the first quarter of school in a dirt overflow parking lot for a student housing project. One morning in late October when I woke, I discovered that the inside walls of the camper shell were wet with condensation. I was, of course, breaking pretty much every rule about how to avoid condensation in a tiny camper, but, hey, I was twenty years old!

Now when a cold rain is pounding on the roof of my tiny trailer and I'm snug as a bug in my down sleeping bag, I might brush my hand along the camper wall to see if it comes away wet with that dreaded word . . . condensation! The good news is that so far my wife and I have had no problems with condensation, but we still pay attention and follow some basic preventative steps to, hopefully, keep condensation from becoming a problem. Perhaps it's because of my early college "homeless" experience, but whenever the topic of condensation comes up, I pay attention--always ready to learn how to stay above the dew point, so to speak.

One of the things I've learned about condensation is that it's all about temperature, air, and moisture. The air that surrounds us usually contains moisture or humidity, the amount depending on conditions we can control fairly well in our homes. However, when we go camping, our ability to strictly control our physical environment lessens. We are outside, and we experience whatever weather conditions that surround us--rain or fog or morning mist. Inside our tiny trailers, we can close the door and windows, but then in that small space, one or two people have a great effect on that enclosed environment just by breathing, sweating, bathing, or cooking. Our bodies are, after all, mostly composed of water and give off moisture even as we sleep. Also, that camper shell that separates us from the environment is thinner and probably less insulated than the walls of our home.

When warm, moist air hits a cool surface, moisture condenses on the surface as droplets of water. Most commonly, we see this on the windows and mirrors in a bathroom when we bathe or shower in cold weather. The fact that bathrooms are generally small rooms increases the likelihood of condensation because the moisture has less air space in which to diffuse.

What is true for the household bathroom is true for a tiny trailer, especially the smallest of tiny trailers, the traditional teardrop. When condensation forms on surfaces, those surfaces can become damp and grow mold, which can cause health problems and cause the deterioration of structures and also damage finishes and fabrics.

Understanding what condensation is and what causes it can help a tiny trailer owner in either controlling or limiting it. As one can imagine, what is true for tiny trailers is also true for boats that have living quarters. Some solutions that work for the marine industry are also solutions for tiny campers. Dealing with condensation problems means finding a way to lessen moisture and to create a buffer between warm air and cold surfaces.

For a more scientific explanation of how and why condensation occurs in your tiny trailer, the Informal CampInn Forum has one thread that includes a thorough explanation by Craig Edevold on body temperature, outside temperature, insulation, and dew point (condensation). Scroll down in the thread to find Craig's comment. Enjoy the color diagrams and prevention suggestions. Below are some key concepts and strategies for avoiding condensation in your tiny trailer.

Air Flow

Air flow is a key factor in limiting condensation, whether it is in a bathroom, a car, or a camper. Moist air has to either flow out of a camper and be replaced by air with lesser humidity, or moist air must flow to a device that removes the moisture. Because a tiny trailer, especially a traditional "mobile bed" teardrop, has such a small volume of air, as moisture in the air increases, condensation will form on cool surfaces, just as condensation will form on a glass of ice water on a humid summer day. There are several actions that can be taken to lessen condensation with air flow management.

  1. Even if a heater is used in your camper, vent the air space. I slightly open the roof vent and at least one side window. Bringing in fresh air and removing moist air can help keep the camper dry. Turn on the vent fan if possible. 
  2. If you must cook in your camper, if possible do so with the windows open and the vent active, removing as much moist air as possible. When I steam vegetables inside my standy trailer, I want the vents and windows open and the vent fan on so that I can see a stream of steam rising up and out the ceiling vent. 
  3. Allow air to circulate around you when you sleep. My standy trailer has storage space beneath the bed, about sixteen inches, so this air buffer lessens the chance of condensation that would occur if I were sleeping directly on the floor. If I were sleeping on the floor, the warm, moist air next to my body would concentrate against the cool surface of the floor, creating condensation. Leave space if possible between the mattress and walls, and create an air buffer between your mattress and a cold sleeping surface. One teardrop owner raised the floor 3.5 inches, creating a small storage space that also acts as an air barrier for his mattress. One problem with this solution is whether there will be enough foot space above the bed once the floor is raised.
  4. Several products are available to create an air barrier between a cold bed foundation/floor and the mattress. These products allow air to circulate, and that is the key. If air circulation is still restricted by a mattress or heavy covers blocking air flow, then results will be limited. 
  5. HyperVent is "a white spun polymer woven into a large open configuration that is bonded to a breathable white fabric layer. This light mesh of polymer does not compress, allowing an open layer of air to form. It is 3/4" thick, allowing plenty of dry air to circulate." Installation includes making sure the mattress does not fit snugly against the wall so that air can freely circulate. This is a product also use for the marine (boat) industry. 
  6. The FROLI box-spring system is used by some RVers for a mattress. Because of its structure, air can also flow because of the individual spring network. The manufacturer states: "If eliminating moisture is your main concern and your mattress feels otherwise comfortable, then it makes sense to choose the lowest height model, the Travel. The Travel is our best seller and it allows for plenty of air to circulate under your mattress. At the same time, your comfort improves greatly with the cushioning effect."
  7. On the Unofficial CampInn Forum is a review of a CVT Anti-condensation Mat. It is similar to the HyperVent. The review includes photos and how the mat was fit to the teardrop. Be aware, though, the review admits to no actual camping experience with the mat.
  8. Open your trailer up during the day and allow it to air out. Take out your mattress to air if necessary.


This article will not address how to build a camper with insulation to lessen condensation. Building a tiny trailer requires a great deal of technical know-how, more than can be provided in this article. A good place to find information regarding condensation, insulation, and trailer construction is at Teardrops n Tiny Travel Trailer forum, where there are specific threads on how to build a tiny trailer to minimize condensation.

It is good to know, however, that a by-product of combustion is water, so using a propane heater such as a Little Buddy will increase the humidity in a tiny camper. If that's the only source of heat (for instance, when boondocking), then you're going to have to juggle heat and moisture, trying to find a balance. One individual said that he burned a candle, which raised the temperature in his teardrop about ten degrees. That "ten degree" number, of course, is relative to camper size, the person's size, outside temperature, and probably a number of other factors that I'm ignorant about. Our homes and many RVs have gas heaters that are vented--both to remove poisonous fumes and also moisture.

I heat with an oil heater I bought at Walmart and which is readily available in many stores. Some people use ceramic electric heaters. Other people use electric blankets or just good down sleeping bags. There are, after all, people who sleep in tents in snowy, frozen conditions. Some people recommend a couple of dogs, but then we're back to "combustion," except that it's calories of food that are being burned, and dogs also give off moisture. Different heat sources affect air moisture, but with all heat sources, the small space of a tiny trailer will still probably require venting moisture out.

A Hands-on Approach

Sometimes a straightforward approach can help. Yes, we'd like to have a situation where condensation is never an issue, but as long as warm, moist air and cold surfaces have an interface, then sometimes we're just coping as best we can.
  1. Wipe the condensation off surfaces, thereby removing moisture. This speeds up the drying-out process. Put the moist towel outside. 
  2. Regularly check beneath the mattress for condensation issues. Raise the mattress and air it out if necessary. Don't allow this situation to continue. Provide an air space between your sleeping foundation and floor. 
  3. Do you have screwheads in the walls that collect moisture? You can buy plastic washers and caps for them that can help insulate the cold surface from the warm air.
  4. One teardrop owner has good insulation in the ceiling but not on the walls. His solution for condensation on the walls in cold weather was cardboard. "Moisture understandably condenses on walls on chilly nights. Bedding gets wet. I glued two flats of cardboard together and cut various sizes to fit the various places in the walls.l slip the cardboard in place at night. It stays dry. It needs to be removed during the day to dry the walls. Bedding stays dry."
  5. Various other DIY "hacks" of board slats, styrofoam slats, interlocking gym mats, insulation foam boards and the like were mentioned in teardrop groups. Whether they would work for everyone is a trial-and-error experiment because camper configurations, bedding options, body sizes, and climates vary so much. A lot of information is available, though, if one searches teardrop groups (or marine groups) for "condensation solutions"--or by searching the net in general.
  6. One teardrop owner uses a product called Damp Rid to take up moisture. I use a small Pro Breeze dehumidifier that doesn't have a compressor. I only use it for warm, humid weather between trips, though, when the trailer is closed up. During cold weather the dehumidifier ices up.
Keeping the moisture outside on a chilly morning

Last fall I camped when the mornings were down to 14 degrees (F) and the campground was covered in a couple of inches of snow. I had several advantages to avoid condensation in my camper, the main being that the standy contains more air space than a small, traditional teardrop. Another advantage is that the bed in my camper is about sixteen inches above the floor, so there was not the situation of having the warmth of the body, moisture, and cold floor coming together and creating condensation. My blankets or mattress never have grown damp. I kept the vent cracked but closed the side window when the snow was blowing during the night. Camping alone, the amount of moisture exuded into the air was less than if my wife were camping with me.

Increase the venting when cooking inside.

Mostly I cooked outside, although I did experiment some with indoor cooking, baking vegetables and feta once in a toaster oven and steaming vegetables inside once with an induction burner. Setting up the standy's dinette table, which is located beneath the ceiling vent, I was able to watch the steam rise, adjusting the fan speed and the amount the side windows were opened to move the steam directly to the vent rather than letting it diffuse. During the evening I did not cook inside in order to allow the heater to dry the air as much as possible.

During the night while sleeping, I felt the walls several times to determine if condensation was forming. The walls remained dry, and the mattress was dry in the morning. If two people were sleeping, perhaps I would have had to open the vent more. If my camper set-up had the mattress on the floor, I think there might have been a problem. I know that my shoes were frozen-cold in the morning, having spent the night sitting on the floor.

I feel fortunate to not have to deal with a condensation problem. The interior space of my "standy" tiny trailer, the fact that the bed is off the floor, and the fact that my cold-weather camping last season was by myself all added to my lack of cabin moisture. I've followed the basic steps above to minimize condensation--mainly providing ventilation and cooking outside as much as possible. I've sifted through suggestions for dealing with condensation and included them in this article, yet whether these strategies will work for you depend on your particular situation--size of camper, number of people camping, climate, and trailer construction. However, the ideas above will hopefully provide a beginning point for coping with camper moisture.

It's best to wake up to morning dew by looking out the window and seeing the rising sun sparkling on the droplets of water gathered on the grass--outside! We wish you all warm, snug, and dry dawns in your tiny campers.

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