Thursday, November 30, 2023


Moisture under bed mattress not good. A solution

By Russ and Tiña De Maris
When you think of mods and upgrades, you may think “big” or “techy.” Well, here’s one that’s less dramatic in approach, but could give you real comfort, particularly if you’re a winter RVer.

We RVers sometimes suffer an obnoxious – and health-hazardous – problem: water condensation under the bed mattress. Most often the problem crops up when the temperature under the mattress is colder than the surrounding room air, so cab-over camper owners and fifth-wheeler folks may be especially plagued with the problem, but others have reported it, too. A wet mattress can lead to mold and mildew – yuck! What’s the fix?

Happily, there’s a quick and simple solution to a wet bed: more insulation. Corrugated cardboard often provides enough chill-fighting. Drop by the “box corral” at a nearby market (furniture stores are great for larger pieces) and pick up enough of the stuff to put down a layer under your mattress.

reflectixAnother admittedly more expensive but less prone to absorbing moisture solution is to use insulated foil. This is the same stuff we recommend for putting up over RV windows to keep out excessive heat. One brand name is Reflectix. Like the cardboard, cut it to size and lay it under the mattress. Some mom-and-pop hardware stores will sell you the stuff by the foot. Ah! Here’s a chance to think out of the (big) box! (Or, if you want to think “in” the really big box, they have it on Amazon.)

No, it’s not big, and it’s certainly not techy. But, hey. If you have a wet bed, this could be the mod that helps you sleep well.


Danger! Check your RV’s mattress for fiberglass! Yes, really!


Russ and Tiña De Maris
Russ and Tiña De Maris
Russ and Tiña went from childhood tent camping to RVing in the 1980s when the ground got too hard. They've been tutored in the ways of RVing (and RV repair) by a series of rigs, from truck campers, to a fifth-wheel, and several travel trailers. In addition to writing scores of articles on RVing topics, they've also taught college classes for folks new to RVing. They authored the book, RV Boondocking Basics.



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Gary Stone (@guest_139784)
2 years ago

I placed a “cut to fit” product called Hypervent. Allows for max air circulation. It’s about 1” thick, lightweight and easy to install.

LugNet (@guest_139770)
2 years ago

I have, and like, a Froli STAR system in my RV. Provides air space under the mattress and support/cushioning. Not many resellers in the USA. Here is the one I ordered some tension expansion clips from to stiffen the support under the hips: The manufacturer’s site (with more options and information) is:
My sleeping space is in the cab-over so anything taking up precious height has to prove itself or it doesn’t stay. The Froli, hands down, stays. More comfort and no moisture problems.

JTilson (@guest_139744)
2 years ago

You lost me with the word “mods”. Is that even a word? I guess there wasn’t enough space to print out the entire word. The last time I saw the word Mods was in the early ’60s with the Mods and the Rockers.

John Koenig (@guest_139801)
2 years ago
Reply to  JTilson

“Mods” or “modding” is a common way to refer to MODIFY something. Many RVers “mod” their RVs to personalize or “improve” (in their eyes) the RVing experience.

Ron Taylor (@guest_139692)
2 years ago

This is what we used in the Airstream:

It has 3/4 inch non compressible polymer loops that allow air flow under the mattress.

Scott R. Ellis (@guest_139683)
2 years ago

The foil only does what any other insulation with an R value of less than 2 would do: maybe enough, but surely not much. Circulate some air under there (“lattice” of some sort as below, etc) or add some actual insulation: rigid foam is about R7 per inch.

Jesse Crouse (@guest_139681)
2 years ago

What do you do when in a diesel pusher as there are access hatches to get to the motor You look directly to the outside.

Gray (@guest_61143)
3 years ago

Also a good idea to ventilate the interior living space a bit more to get rid of moist air from breathing, cooking, and perspiration. Crack a window or two, and open the roof vent a bit. If any condensation is showing on the windows, it’s a sure bet that it’s also collecting in the dark, unvented places like behind seat cushions and under the mattress.

Fred (@guest_60538)
3 years ago

The insulated foil doesn’t get rid of the moisture in the mattress. It just keeps the temperature high enough that it doesn’t turn to water. You have to have air flow around & under the mattress to move the moisture out. I drilled 3″ holes in the base board of the bed pedestal & on the sides of the pedestal storage area. I then hooked up a computer fan to one of those side holes. It draws air through the pedestal & sucks air from the bottom of the mattress. No more moisture stains on the wood base of the mattress. Air movement is essential to solving the problem. Also leaving your bed unmade during the day will help some of the moisture to escape, instead of “making up the bed” & sealing your body’s moisture in the mattress. Also turn your mattress head to foot every 6 months. The moisture problem has become much more prevalent in the past few years with the increased popularity of foam mattresses.

Brian S. Holmes (@guest_60558)
3 years ago
Reply to  Fred

The same idea I cut 5×8 non lovered air duct grills from Home Depot on the bed box. One on each side. Air that moves carries away the problem.

Barry (@guest_60530)
3 years ago

A wet mattress was always and issue in my 5th wheel until I decided to drop by my local hardware store. I purchased some thin wood lattice material, cut it to fit the bed deck and created a very comfortable and ventilated base. No more moisture problems and the bed temperature was much more even as well.

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