How to Keep Moisture Out of RVs in Winter

When you get an RV, you need to think about a lot of details: price, gas mileage, how to drive it, where to park it, and all the exciting adventures you can use it for. But there is one very important thing that you might not immediately consider but is vital for keeping your RV in good shape — moisture control.  
 
Much like in a traditional house, too much moisture in an RV can not only make the interior uncomfortably humid, but it can also cause damage if the moisture is not dried away or allowed to escape. This can be especially problematic for those using their RVs in the winter or storing them in colder climates.  
  
Thankfully, there are a few straightforward ways to combat winter moisture and keep your RV cozy and dry. Let’s dive into some of the best tips for how to keep moisture out of RVs in winter and how to stop condensation in a camper to protect your RV all season long.

1. Understanding the Problem of RV Moisture 
2. Preventative Measures for RV Moisture 
3. Practical Tips for Preventing RV Moisture 

The first step to solving a problem is to understand the reasons behind it. The issue of RV moisture in the winter is no different.  

Moisture in an RV is created when the warm air within the RV encounters colder air from outside. The vapor in the air condenses as it cools, forming drops of water (remember the water cycle from science class?).  
 
If the moisture can’t escape the RV, the resulting droplets will settle on the RV’s cooler surfaces, such as windows, walls, and countertops. This vapor can be generated by cooking on the stovetop, taking showers, or merely breathing inside the RV. 
 
If you’re thinking a little water won’t hurt your RV, you may want to think again. Too much moisture in an RV can cause a multitude of different problems. Condensation on the RV windows limits your visibility. Moisture build-up can cause an RV’s metal components and electrical systems to corrode, while wooden furniture may swell and warp, making them difficult to use and move.  
 
Perhaps the most serious issue moisture can cause is mold. Along with giving your RV’s interior an unsightly stain, mold can give you allergy-like symptoms such as headaches, congestion, and a sore throat. If you or your family member have a compromised immune system or other health condition, they can cause more serious health issues. 
 
Essentially, moisture build-up has the potential to create a lot of damage you want to avoid. You don’t want your trip to get delayed because you have to repair or replace most of your RV’s interior!  

The best way to solve a problem is to prevent it from happening in the first place. Now that we know what causes RV moisture build-up, let’s look at how you can keep your home-away-from-home nice and dry. 

An effective method of preventing condensation and humidity in an RV is to get the moisture out and keep the air moving. This is why proper ventilation in an RV is so important, as it allows the water vapor to escape outside instead of getting stuck on cold surfaces. Functioning vents and fans can also help control temperature and get rid of bad smells.  
 
A particularly handy piece of ventilation equipment is the Furrion RV roof vent fan, a high-powered fan that can be placed in travel trailers, 5th wheel trailers, and other RVs. Easy to install and operate, the Furrion fan efficiently moves air out of and around the RV. Its speed is adjustable for different temperatures, and its lid can be manually closed in the event of rain or snow.  

Another ventilation device you may want to consider is the 360 Siphon RV roof vent cap. Attached to the RV’s holding tanks (a container for the wastewater from the shower, toilet, etc.), the 360 Siphon is designed to only create an updraft, forcing the air within the tank outside. This prevents the air from seeping into the RV itself and bringing not only moisture, but unpleasant smells with it.  

Sometimes you can’t get rid of every last bit of excess moisture with ventilation alone. If that’s the case, you may want to consider using a portable dehumidifier to keep your RV’s humidity under control. Dehumidifiers are, like their name would suggest, devices that remove moisture from the air around them. They do this by drawing in vapor-rich air with a fan and moving it through refrigerated coils, cooling the vapor until it condenses into water droplets. The water then falls into a storage tank as the newly dried air exits the device.  
 
Just remember that dehumidifiers for RVs in winter will only work if there’s room in the tank for more water. While some types can be constantly emptied via a hose attachment that drains the water into a sink or shower drain, others will have to be emptied manually.  
 
Of course, if you’re planning on storing your RV over the winter, you might not have access to power. Not to worry — there are several electricity-free dehumidifiers to choose from.  
 
Rechargeable dehumidifiers do not need to be plugged in to work. You will just have to remember to…well, recharge them.  
 
Chemical compounds such as calcium chloride and silica gel can absorb water out of the air. You can purchase these as pouches or buckets. However, they are only effective in small spaces and will need to be replaced after use.  
 
For those of you with a green thumb, there are plants that absorb moisture straight out of the air! These include cacti, orchids, peace lilies, and spider plants.  

Improving your RV’s insulation prevents moisture build-up in two ways: by stopping unwanted water from quite literally slipping through the cracks, and by keeping the RV warm enough to avoid cold, condensation-friendly surfaces.  
 
First step: check the roof. Inspect the roof seams, vents, and air conditioning units for any gaps that vapor, or rainwater could slide through. Use sealant or tape to close any holes you find. Don’t forget to check your current sealant for cracking or dryness. If you notice any, scrape away the old sealant and replace it. If your RV has a skylight, consider getting an insulating cover.  
 
Next, let’s look at the windows. If your windows can open, check that they can also be fully closed. Examine rubber seals for any tears and sealants for any cracks. Replace anything that shows signs of wear-and-tear. If your windows are single-pane, you may want to consider replacing them with double-pane windows, as the extra layers of glass help keep the heat in and the cold out. 

Don’t forget the door! Check the sealant for any cracks and shrinkage. An easy, cheap way of keeping your doorway insulated is a door snake — an elongated cushion that rests along the bottom of the door, blocking any drafts.  
 
Note: Whenever you go to replace old sealant, make sure you buy the correct type. There are different kinds of sealant for RV roofs, walls, and windows.  
 
If you really want to go the extra mile, you can upgrade the insulation of the RV itself. There are generally three kinds of insulation to consider: fiberglass, rigid foam, and spray foam. These types of insulation vary in their cost, ease of installation, moisture resistance, and lifespan. So, you will need to decide which is best for you. Since we are discussing how to best protect your RV during the winter, you may want to look closely at rigid foam insulation, as it’s especially durable and waterproof.  

Finally, stay vigilant! Make regular checks of your RV for any signs of moisture build-up or ventilation/insulation issues. If you find any leaks or problems, fix them as soon as you can. A little effort now can prevent a lot of damage (and headaches) later! 

Now that we’ve looked at how to prepare your RV for the winter, let’s look at what you can do to prevent RV moisture build-up as the temperature cools down.  
 
As we’ve already mentioned, ventilation is key to preventing excess RV humidity. Along with the RV’s ventilation systems, you can crack the windows open to keep air moving and allow any moisture to escape. If your windows have bug screens, make sure to clean them beforehand for maximum ventilation.  
 
You can also keep the air moving with fans — these are especially useful for smaller, tighter spaces that the RV’s ventilation can’t quite cover.  
 
If you’d rather not get your feet chilly with increased ventilation, you can try going in the opposite direction. If you crank your RV’s heat up high enough, then you can actually warm up the cooler surfaces within the RV, preventing water vapor from condensing on them. This likely won’t stop RV condensation in winter completely, but at least you’ll be nice and toasty! 
 
Speaking of heat, consider exactly where you’re getting your heat from. RV furnaces usually run on propane, which produces more condensation than other heat sources. These furnaces are vital for keeping your RV’s tanks and water systems from freezing, so shutting them down entirely is often not a good idea. However, consider using an electric space heater when and where you can for a drier heat source. Just make sure to use it safely! 
 
While your RV is always going to have some moisture in it, you should avoid activities that generate moisture excessively. These include cooking on the stovetop, hanging clothes to dry, and long, hot showers. Instead, you should:

• Cook food in the oven or try cooking outside 
• Use clothes dryers 
• Take your shower in campground facilities. If these are not available, shower quickly

Take note of any dark, poorly ventilated spaces in the RV where mold may easily grow, such as closets, cabinets, and under or within mattresses. Ventilate these spaces whenever possible by leaving closets and cabinets open and airing out your mattress. Use fans and dehumidifiers to circulate the air further.  

If you plan on merely storing your RV outdoors for the winter, you should still visit it regularly to check for any signs of moisture build-up. Cover your RV with a well-secured but breathable tarp. This protects the RV from the elements while also allowing moisture to escape. 

RV moisture control is an easily forgettable, but vital part of owning an RV, especially in the colder months. Moisture can build up within an RV, causing massive damage and allowing harmful mold to grow.  
 
In order to keep your RV in good shape, you need to perform regular maintenance on the ventilation and insulation, along with using dehumidifiers and ventilation devices such as the Furrion fan and the 360 Siphon. Small and simple actions can save you time and money in the long run.  
 
Remember, your RV is your home-away-from-home. Taking care of it now means you can enjoy it for many years — and adventures — to come!