How to Keep Moisture Out of RV in Winter

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Moisture is the enemy of RV owners.

These may sound like strong words, but it’s important to understand that the condensation observed pooling on the windows reflects the level present inside your camper, trailer, or motorhome.

The winter months represent a far more substantial challenge to keep moisture and condensation at bay.

Condensation in RV: What Causes It to Happen?

Drier environments suffer less than humid ones do, but moisture is still created when we breathe oxygen, enjoying a hot shower, preparing a hot beverage, or cook. Given that these are all-natural, necessary activities as an RVer, some dampness is inevitably going to be introduced inside the living environment.

Quite often, you can feel the condensation because the walls or other surfaces are damp or moist to the touch. This indicates a major moisture problem that needs to be sorted out ASAP.

The situation becomes far worse in the winter months. Colder, damper air contains additional moisture that doesn’t just show on the windows or windscreen, but also gets inside the RV’s walls, flooring, substructure, furnishings, seating, window decorations, and bedding too.

Furthermore, it can lead to health problems from breathing in mold or mildew spores. These bacterial worries develop rapidly in wetter, colder environments.

How to Keep Moisture Out of RV in Winter

While you may not have much of a problem during the summer, condensation and moisture in winter is another matter entirely.

To properly assess how much moisture is presently inside your RV, it’s necessary to use a digital tool to do so. A hygrometer can confirm not just the internal temperature but also the level of humidity in different living areas of your camper, trailer, or motorhome.

If you’re unsure how bad the problem is, then this is the answer to making a quick determination about it. Also, you can regulate the measures taken to keep moisture levels at bay through the winter months when they can be the most damaging.

There are different indoor hygrometer models. The ThermoPro TP50 Digital Hygrometer is a reliable one. Be aware that some temperature sensors only confirm the temperature and not the humidity level.

Also, some models only perform sensor checks indoors, whereas other ThermoPro models provide sensors for both indoors and outdoors. This is useful to see how well your heaters are keeping the cold out or a dehumidifier is removing moisture compared to the external readings.

ThermoPro TP50 Digital Hygrometer Indoor Thermometer, Humidity Gauge & Temperature Humidity Monitor

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What follows is a series of tips on keeping moisture from the RV during winter:

Use the Overhead Fan(s)

RVs usually have one or two overhead fans – larger, newer RV models typically have a roof fan at each end of the living space.

While you may mistakenly believe that the fans will let cold winter air in, the idea is to keep ventilation flowing. This will remove stale air and allow fresh, oxygenated air to circulate. Most of the time, this will still be drier than the current internal air when living in the RV.

So, keep the fans running. If they’re broken, get them fixed, or replace them with new ones.


Switch to an Electric Heater

While your RV may come fitted with a propane furnace, these introduce additional moisture inside the living space.

An infrared space heater is much better for providing consistent, dry heat. This warms up the air to keep it toasty in winter and dries the remaining air to eliminate a fair amount of moisture along with it.

Your heating costs will likely rise a bit if you’re at a campground plugged into electric hook-ups, but it’ll keep your RV safe from mold and mildew growth.

We recommend the Heat Storm HS-1500-PHX-WIFI Infrared Heater which can mount on a wall, is Wi-Fi and app-controlled and can use up to 1,500 watts. It’s also safer for children because its exterior grill doesn’t heat up.

Heat Storm Wi-Fi Infrared Heater, Wifi Wall Mounted – HS-1500-PHX

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Get an Indoor Dehumidifier

An indoor dehumidifier can suck up moisture and collect it for later disposal.

These are either machines that extracting moisture from the air or are a box of fancy moisture-absorbing stuff (desiccant; a hygroscopic material).

Moisture Absorber

The cheaper option is to purchase a pack of moisture-absorbing material and cups to store them in the interior of your RV.

The DampRid moisture absorber comes in unscented and scented versions. The four packs of 10.5 oz. filled cups include a hanging bag to place inside your wardrobe to keep clothes drier too.

Each cup can be refilled and should last 6-8 weeks.

Electric Dehumidifier

An electric dehumidifier is the better option of the two.

They can be purchased in different sizes and collection capacities. Matching the model’s capability to your needs is important here. If you’ve got a camper that is damp and cold in winter, then a more powerful dehumidifier will serve you well. When there are some issues in one or 2 places inside the RV, then a mini dehumidifier will be fine.

These units use little power but manage to absorb an impressive amount of moisture each day. A water reservoir collects the moisture and better models like the Tenergy Sorbi 1000ml Air Dehumidifier provide alerts and shut off when they need to be emptied.

Tenergy Sorbi 1000ml Air Dehumidifier. Air Purifying, HEPA Filter. (Auto Shutoff w/Touch Control and Adjustable Air Speed)

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Use a Laundry Mat

Unless your washing machine also dries the clothes exceptionally well, you’ll be hanging them up to dry. During the summer, an exterior clothesline was fine. However, when it’s reached freezing temperatures, the clothes will never get dry. Then you’ll be tempted to hang them indoors.

Unfortunately, damp clothes hanging up to dry inside your RV during winter is a bad plan. It introduces more moisture, rather than removing it.

Instead, switch to using a laundry mat to wash and dry your clothes in winter. It will take a little longer, but it avoids creating additional moisture problems.

Reconsider How to Cook Meals

Cooking on the stove, bringing vegetables to a boil, and having stews simmering may sound great, but the released steam adds moisture through the cooking process.

Here are some alternative cooking methods for RVers in winter:

Slow Cooker, Instant Pot, or similar – These cookers contain water during the cooking process to ensure the food doesn’t dry out over extended cooking times. Once the food is cooked, it’s best to disconnect the power and carry them to an outside table before carefully releasing the lid. That way, their trapped steam won’t invade the RV.

Oven – The oven is an efficient way to cook food without adding moisture into the bargain. A convection oven is preferable over a propane-based one because the energy source generates less moisture as it cooks.

Outdoor BBQ – An outdoor cooking option – any that you can come up with – is good on non-rainy days. Harder to do because of the colder temperatures, for sure, but it won’t add extra moisture inside the indoor living area. And if you eat the steaming hot food outside too, even better.

Keep Cabinets Open More Often

Cold and moisture get trapped inside cabinets even when the coach is being heated.

To avoid anything inside the cabinets like clothes, food, electronics, or other items from suffering from the moisture effects, keep the doors open at times when they won’t cause an obstruction. This will prevent the trapping of colder air inside and avoid items from smelling damp or musty too.

Insulate the Windows

Putting up a film covering the windows can act a little like double glazing where the air is trapped between two panes of glass.

In this case, the film adheres to the inside of the window’s frame. This is achieved by using a hairdryer to get it to stick to the edges and create an effective seal.

The 3M Indoor Window Insulator Kit is an ideal all-in-one solution. Do consider the film size dimensions if ordering, because you’ll need enough material to separately cover multiple RV windows.

3M Indoor Window Insulator Kit, Window Insulation Film for Heat and Cold, (5.16 ft. x 17.5 ft. for 3 ft. by 5 ft. Windows)

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Closing Thoughts

How many types of moisture capturing or moisture reducing products are needed largely depends on the extent of the problem. If you have condensation and excess indoor moisture due to humid summer environments, then it stands to reason that you may have similar issues in damp winters too.

The majority of RVers must deal with moist air and condensation problems and find it’s best to implement solutions to avoid moisture-related damage to their home.

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