RV Condensation And 14 Ways To Prevent Mold In Your Trailer


Why You Should Care About Condensation On Your RV Windows


When water vapor cools and becomes liquid, condensation is the result. So where does water vapor come from? Not only is it already in the air based on how humid it is, but it’s also created when you breathe, cook and shower in your trailer.

But why does condensation show up on your windows, metallic parts, and sometimes even make your floor feel wet? Because it sticks to cold surfaces. If it’s cold outside and there’s a lot of water vapor in the air inside your camper, it will create condensation and stick to your windows, and that’s when you see it.

The reason why it’s something that you should care about is that you basically have water hanging out in your trailer when the humidity is high. This water might not seem bad at first, but over time this moisture can cause issues with mold, rotten wood, corrosion and a trailer that is water damaged.

Just because you haven’t seen any mold doesn’t mean it’s not there. It can start growing in the walls, under your shower, mattress or floors, and other places you don’t see every day. This is why it’s important to take care of and reduce condensation and moisture inside your RV.


How To Monitor Relative Humidity In Your RV


The first step to reducing moisture and water vapor in the air inside your trailer is knowing how much there is. We want to stay between 35 and 50 percent humidity which is the ideal level both for our bodies and to stop mold from growing.

When it comes to monitoring the relative humidity inside your RV, a weather station will be the easiest way. We’ve written a post about the best weather stations for RVs that you can find by clicking here, but if you want the most basic one that will tell you the temperature and humidity both indoors and outdoors, the ThermoPro TP65 is a great choice that runs on batteries. If you want to know the indoor humidity and temperature, ThermoPro also makes an even simpler version called the ThermoPro TP50.


Ways To Lower Humidity And Reduce Condensation  In Your RV


When you know how humid it is both indoors and outdoors you can take steps to control it. Now, please don’t go nuts trying to follow all these tips down below, but keep them in the back of your mind and use them as needed.

Let’s get to the tips.

Exhaust fans

Most trailers come with a kitchen and a bathroom fan. Using both of these whenever you are cooking or showering is a good way to reduce relative humidity, which will help reduce condensation.

Other times it can be a good idea to run your exhaust fans is while you’re doing dishes, boiling water, or bathing.

While most trailers come with a bathroom fan, they’re often very tiny and useless in terms of air circulation. They’re relatively easy to upgrade though, and two popular upgrades are the Maxxair fans and Fan-Tastic Vents. I have seen more trailers come pre-installed with one of these higher quality fans lately though, so if your trailer is relatively new, you might already have a great one.

Wet Clothes And Towels

Leaving wet clothes and towels hanging in your trailer to dry will release that water into the air. If possible, hang your towels and clothes outside. If it’s not possible, hang them in the bathroom with the exhaust fan on, and the door closed. This way the water vapor won’t be spread as much around the whole camper and the exhaust fan will suck out the warm, humid air.

Dehumidifier

A small dehumidifier can decrease the relative humidity in your trailer. I bought one a couple of weeks ago when we started having condensation issues, and so far it has done a great job at keeping the humidity inside our 30 feet trailer low through rainstorms and high humidities outdoors. I am going to write a review about my specific dehumidifier later on, but the exact model I bought can be found by clicking here.

Remember that what you’re looking for is a dehumidifier, not a humidifier that does the opposite of what we want.

Inside Temperature

The temperature inside your RV matters. By raising the temperature in your trailer, there will be less condensation on your windows. If you can’t run a heater, it can be as easy as closing the curtains or your blinds to increase the temperature around your windows.

Cooking and showering

If you’re in high humidity areas and the weather allows, cook outside! Sometimes you can even shower outside, or at least use the campground facilities if you have access to them.

If you have to or would rather cook or shower inside, remember to turn on the exhaust fans to not fill the air with excess water vapor. Another thing about cooking is using lids that will reduce the water vapor released from steam in the air.

Circulation

A crucial thing to do is to circulate the air inside your trailer. This is especially important for closets and cabinets. By leaving the door slightly open to these, the temperature will be the same as in the rest of the camper, which will prevent condensation. Opening a window can let out hot moist air as well.

Doors and windows

Opening a window or a door can help to ventilate and reduce condensation as long as it’s not raining outside. This will help to circulate the air and bring in fresh air.

This is another reason to have a weather station like the ThermoPro TP65. Knowing whether it’s more or less humid outside than inside and if you should open a window or not.

35% – 50%

By monitoring and making sure that the relative humidity inside your trailer stays between 35 and 50 percent, you can prevent and reduce condensation. Condensation can and will still happen, but this way you can at least make sure that you’re doing what you can to prevent mold from growing.

There is no need to panic if the humidity is suddenly at 70%, but letting it happen over and over without doing anything will give mold time to grow, and the risk is higher that you’ll have to deal with it in the future.

Moisture absorber

Moisture absorbers like DampRid can be placed around your trailer to attract and trap excess moisture from the air. I recommend putting these in closets and cabinets where there might be excess moisture.

When are DampRids better than a small dehumidifier? A mix of both is the best, but if you’re boondocking a lot and don’t have access to electricity (which you need for a small dehumidifier, around 20-100 watts depending on choice), DampRid will be an excellent way to control humidity. They’re not as effective as a good dehumidifier, but they’re certainly better than nothing.

LED lights

Incandescent lights produce more heat than LED and fluorescent lights and can contribute to condensation in your roof with prolonged use. Installing LED lights might seem expensive at first, but with longer lasting lights and less heat, you will save money in the long run.

Wet areas

If there is condensation on your windows or vents, wipe it off. The damage from condensation and high humidity occur when that water gets to drip down and get stuck in areas with no circulation. So grab a towel, wipe off your windows, and hang that towel outside for it to dry, or hang it in your bathroom with the exhaust fan turned on.

Mattresses, closets, cabinets

Have you ever seen a moldy mattress? It happens because of the moisture from body sweat that gets stuck in the bed. Keeping damp clothes in a closed closet can do a lot of damage on its own even if the humidity in your trailer is at reasonable levels.

As mentioned above, closets and cabinets are also areas where condensation can occur if you’re not careful. An easy way to reduce condensation in these areas is to leave the door open to the air can circulate, and the temperature can increase.

Air conditioner

One of the best ways to reduce humidity inside your camper is to run the air conditioner. Air conditioners cool houses and trailers by removing heat and moisture which will lower humidity.

The downside with air conditioners is that they use a lot of energy so this will only be a viable option if you have hookups or a generator.

Planning

It might seem obvious to some, but others forget that some places are much more humid than others. The southeast is especially known for being more humid.

A good weather forecast will often tell you the expected humidity. If you won’t have access to electricity to run a dehumidifier, you might want to consider the place that is expected to be less humid than the other. Don’t change your trip to where it adds 10 hours of driving of course, but use common sense and plan and both you and your trailer will be more comfortable.


I hope you’ve gotten a better understanding of humidity, condensation, and ways to take care of it. Taking care of it before it becomes an issue will save you lots of time and money.

Let me know if you have any thoughts about the post, something to correct or something to add. Together we can help each other keep our campers mold-free!

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