One of the problems with sleeping in a small, contained space like an RV or van is the tendency for moisture to build up inside. This is usually most visible on or around the windows. But did you know that it can also build up under your RV’s mattress? When it does, it can lead to mold that causes odors, damage, and health problems! So, preventing moisture under RV mattresses is absolutely critical.
In this post, we’ll tell you how you can prevent condensation from forming under your RV’s mattress so you can avoid the growth of mold not only under your mattress but also throughout the confined space where you sleep and live.
How to Prevent Mold Under Your RV Mattress
Science tells us that warm interior air plus cold windows/walls equals the development of condensation that can lead to mold growth. Science also tells us that moisture/condensation from showers, propane appliances, and even breathing leads to mold and mildew in certain areas unless it’s prevented. Moisture can become a real enemy of RVers, but there are things we can do to conquer that enemy, as we noted in our posts on RV ventilation and RV dehumidifiers.
A very common area of concern for RVers and others living in small spaces is under mattresses. Not only is this area ripe for the development of mold and mildew, but it’s right where we lay our heads to sleep and breathe for hours every night. So, preventing moisture under your RV mattress is very important.
Here’s some information from the EPA concerning moisture and mold in a home. As for our homes-on-wheels, there are several ways we can win the battle against moisture where our RV mattresses are concerned:
Use a Waterproof Mattress Cover
Waterproof mattress covers offer a barrier against moisture so that it never has the opportunity to reach your mattress. This is among the least expensive measures you can take to prevent moisture from building up under an RV mattress, but you may need to take additional measures as well.
When shopping for a waterproof mattress cover, be sure to carefully read user reviews to make sure the cover you choose isn’t noisy (so that it won’t disturb your sleep), and that it actually offers protection from moisture reaching your RV mattress. Here are a few options to consider, but be sure to be careful to purchase a cover that will fit your RV mattress, as RV mattress sizes aren’t always the same as traditional mattress sizes:
No products found.
- Waterproof - The back is coated with advanced waterproof membrane, which will protect your mattress from all kind of liquids, prolonging the life of...
- Fitted Sheet Design - The elastic skirt makes it easy to put on and off your mattress
- SIZE LISTED TO CHECK BEFORE PURCHASE| This size fits 38 wide by 75 long. Depth is a stretch wall but will not work if your mattress is Iess than 9 or...
- COMPLETE PROTECTION| This is not a fitted sheet style cover. This covers zips closed on all 6 sides & protects your RV and camper mattress from Dust,...
Monitor Humidity Levels In Your RV
Humidity levels can rise quickly and discreetly in an RV environment. As we mentioned earlier in this article, showering, using propane-fueled appliances (like stovetop burners), and simply breathing can increase the humidity levels in a small living space.
Running vent vans and regularly airing out the rig to replace that moist air is generally very helpful. But depending on where and how you camp, you may need to look into an RV dehumidifier. These are available in various types and for all sizes of RVs. For more information, see our post on the best RV dehumidifiers where you’ll find de-humidification options for every budget.
Use an RV Mattress Moisture Barrier
If using a waterproof mattress cover doesn’t stop the problem, you may also need to consider getting a moisture barrier for your RV mattress. These products fit between the mattress and the bed support/platform and allow air to flow. This may be sufficient to keep moisture, mold, and mildew from building up under your mattress. There are several different options for mattress moisture barriers depending on what your budget constraints may be.
We’ve read about people using something as simple and inexpensive as a slab of cardboard, or pieces/blocks of wood, placed between the mattress and bed frame. The goal is to allow air to circulate so that any moisture under your RV mattress can escape.
You can also opt to buy a good RV moisture barrier that’s specifically designed to keep air flowing so that moisture (and thus mold and mildew) is unable to develop. One popular option is the Hypervent Aire-Flow from MattressInsider. It’s made of a 3/4″ thick layer of industrial-grade woven polymer material that’s bonded to breathable fabric. Placed underneath your RV’s mattress, it provides a path for air to circulate and prevents condensation from forming.
You can order the Hypervent Aire-Flow moisture barrier based on the size of your RV mattress from the MattressInsider website. Be sure to use the discount code below to save yourself some cash!
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After 11+ years of full-time RVing, our original RV mattress was worn out and no longer comfortable to sleep on… but with our new, custom-made one from MattressInsider we’re sleeping soundly again!
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Show LessThis video shows you exactly how this high-tech RV mattress moisture barrier underlay works:
Use a Ventilated Base or Foundation
Just like the moisture barrier above, having a base for your RV bed that offers ventilation beneath the mattress will help to prevent moisture from building up. If the foundation for your mattress isn’t ventilated with holes or slats or some other opening that allows air to circulate beneath the bed, moisture is much more likely to accumulate, causing issues with mold and mildew relatively quickly.
This is why many people who build out vans use frames/bases with slats… or they drill holes into the wood that serves as the base for their bed. It’s all about ventilation. Good ventilation is the key to keeping moisture from getting trapped in and beneath the fibers of your RV mattress.
Rotate Your Mattress Regularly
Finally, rotating your RV mattress regularly is essential not only in terms of the sleeping surface the mattress provides (keeping soft spots and indentations from forming) but also as a mold prevention method. Flipping the mattress regularly helps to keep moisture that has accumulated from creating mold.
When you turn the mattress to air out the side that was on the bottom, this allows that side of the mattress to dry out. If you camp in areas with high humidity, though, be sure to flip your mattress more frequently (normally, you want to flip it once or twice a year to prevent soft spots… for mold problems, you may need to flip it as much as once every couple of weeks, depending on how quickly moisture builds up).
NOTE: this can be difficult to do in some RVs, so if your mattress isn’t able to be flipped regularly, you can remove the linens and lift one side of the mattress so that the underside is exposed. Placing a fan beside the exposed underside and running it for several hours should help to dry out the underside of the mattress.
With all of that said, it’s simpler (though also more expensive) to use a mattress cover and/or an under-mattress moisture barrier to prevent the problem in the first place. Any way you slice it, moisture is not a friend to RVers or to anyone living in a small, confined space. Dealing with moisture before it can turn to hazardous mold rendering your rig unhealthy and in danger of permanent damage is key!
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Walter
Monday 27th of October 2025
Do have any experience or thoughts on using an air mattress instead of a standard mattress? Thinking it could reduce weight and can be deflated and refilled on a daily basis if need be.
Walter
Tuesday 28th of October 2025
@TheRVgeeks, awesome thanks so much.
After viewing your video of your new trailer, I thought an inflatable might be a consideration for a Murphy Bed. Just a thought. 🤔
TheRVgeeks
Monday 27th of October 2025
Hi @Walter. We don't have any personal experience with using an air mattress on our RV's bed, though we DID have a queen size air bed for guests to use in the living room on our old motorhome (no room for guests on our new trailer, LOL!). Friends of ours, though, had a Sleep-by-Number mattress on their Winnebago and loved it. They did just move it to a new trailer, and because of lack of insulation in the pass-through storage bay that runs beneath the bed they did have some issues with a bit of moisture build up under the mattress. So an inflatable won't solve the problem, though (since it can be deflated) it is easier to manage to remove it and/or lift it so air can circulate and allow things to dry out.
Rhonda
Monday 20th of October 2025
My mattress always feels wet on the underside leaving stains on the bottom edges of the sheets. It sits on carpet. Does that cause more moisture to build up? We've been searching for a leak coming in from the window above the bed.If we have a very wet spell it doesn't seem to affect the wet areas. Haven't seen any areas where it leaks. Should we remove the carpet and install the moisture barrier you referenced above? Thank you in advance.
TheRVgeeks
Monday 20th of October 2025
Sorry to hear about that, Rhonda. We don't think that the carpet would cause more moisture to build up, so that's not likely the culprit. Since you've likely eliminated the possibility of a leak, it definitely sounds more like an issue with moisture/humidity. You could try to increase ventilation by making sure you leave a roof vent fan open and on low, and maybe crack a window or two in the bedroom to try and help bring cooler, drier air in. But if that doesn't solve it, then a moisture barrier would likely be the best bet. You shouldn't have to remove the carpeting under the bed unless it causes an issue... but we wouldn't expect it to.
Allan
Sunday 19th of October 2025
Just a quick additional comment. Many gel or foam mattresses are made from multiple layers with different characteristics. These types have a stiff layer on the bottom and a more flexible and comfortable layer on the top. So they're not designed to be flipped over.
Bruce
Sunday 19th of October 2025
We had mold so we put a waterproof cover over the mattress and underneath it we folded one of those outdoor plastic woven carpets to provide air circulation, so far it works. I’d like to figure out how to insulate the pass through storage area and / or warm it up some but that’s a major job.
Bruce
Saturday 15th of November 2025
@TheRVgeeks, Thanks for sharing the video, that's given me some ideas as to how to proceed. Much appreciated!
TheRVgeeks
Sunday 19th of October 2025
Hey @Bruce. Glad you found a solution to your problem. Insulating the pass through storage area would definitely help to keep condensation down. If you haven't seen it, check out Matt & Diana of Adventurous Way's video about insulating the pass through on their trailer: https://youtu.be/Mh7BAfa79Wc?si=sKfvUJjpCfsAr9UW (based on their experience and input, Outdoors RV has since changed their manufacturing to insulate that area better). It might help you get some ideas to help make the project a little easier.
Ron Carter
Sunday 19th of October 2025
I have used 12" x 12" Dri-Dek Panels from West Marine. Model # 19616648 Mfg # 00M25PWE