VanDweller Community Forums

Full Version: Mattress platform condensation
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
Pages: 1 2 3 4
One of the best days of my Van ownership was when I took a sawzall to the jackknife fold out conversion van back destroying Sofa bed and put it in the recycling bin.

I had made a large plywood platform and had a nice piece of expensive foam made up with a custom denim cover.

Super comfortable, but after a few weeks of wintertime sleeping on it, I happened to notice it felt wet underneath it, very wet, and the beginnings of mildew were forming on my new expensive mattress.

I removed the denim cover and hand washed it as I was in Baja at the time and set the mattress out in the sun to dry.

Basically the plywood platform remains cold, the mattress is warm and the body respires a good amount of moisture, and it congregates on the bottom of the mattress, and does not get a chance to dry out.

I devised a method to lift up the mattress so air can circulate and moisture evaporate, and do so every two days in the wintertime and have not had subsequent issues with mildew growth.

The condensation is less of an issue in the summer but still there.

Just a warning to those who are making plywood platforms for their mattress.  Design a method so air can circulate under the mattress every day or two.

Some products exist to allow air to circulate under the mattress without lifting it.  They probably also make the bed warmer.  I guess some sort of moisture barrier could be used on top of the mattress to repel the absorption of humidity in the first place too, but the bottom of the mattress will still benefit from being aired out.
You might try a wool blanket between the mattress and the plywood. Then another between the mattress and the bottom sheet.
I was considering acquiring some of this, but lifting the mattress  to dry naturally is free
Would a slat design work too? 
I've been wrestling with the dampness/mold problem with my setup. I'm sleeping in the front overhead extension of my slide-in truck camper and it's pretty hard to mitigate the dampness. Insulation (hard foam) underneath helps, but by no means eliminates the problem. Walls on 3 sides and a wooden stringer along the front makes for a kind of 'bathtub' which holds in moist air. The best solution would probably be to take a page out of the old-timers book and make a variation of the canvas cot, but stretching that black mesh often found on lawnchairs the width/length of my bed. Thin foam on there and plenty of air circulation to be had. Would just have to drill holes along that stringer to allow for the egress of damp air. Now, all I gotta do is get of my lazy white butt and to work; maybe I'll sleep on it a bit. ...Willy.
Slats would help, but compromise strength, depends on how you build/support the bed platform.

Think about how regular mattresses and box springs are built,  Those little"speakers" by the mattress handles and the box spring covered in a airy fabric and open to the bottom.

Too bad this stuff is so expensive for what it is.  I bet it would still enjoy some forced air circulation.

I'm sure some thick coarse wool would help isolate the mattress from the cold platform

Unsealed plywood would absorb the moisture and mildew/mold spores. 
An cheap and easy solution is to drill 2 doorknob-size holes in the platform,  get a heavy duty sheet of plastic, lay it over the mattress, then pull it down over teh sides of the mattress and staple it underneath the platform so the plastic totally encases the mattress and is secured to the underside of the platform.  The doorknob size holes allow air trapped under the plastic to escape  so it doesn't poof up. I did this to my beds and have never had a moisture problem because any moisture from your body never touches the mattress.  It also prevents the mattress from being ruined if you forget to close the roof vent in rain. It takes about 2  nights to get used to the sound of the plastic when you roll over, then it becomes a nonissue. Cost is about $5.00 for the plastic.
Thanks for posting.  It is something worth watching.  My bed platform is a piece of painted 3/4 inch plywood.  I flip the mattress (traditional twin type) every month and haven't seen any signs of mildew (yet). 

There have been days with a lot of moisture gathering and freezing on the windows.  Weather permitting, I occasionlly heat up the cab and cargo area of the van and run air through for an afternoon to dry it out. 

Would the bed moisture problem be more prevalent in the southeast / coastal areas where humidity levels tend to be high or...  ?


The higher the humidity and the bigger the temperature between plywood and mattress the more condensation will build.  If one uses a heater which heats the underside of the bed platform the issue will not be as severe.  Mine has very little air circulation under the bed  platform, and very light insulation on the walls and floor in the back under the bed making the issue worse for me as it is easily 15 degrees cooler under there than the airspace above the mattress, before I even get in bed.

Many factors involved though, such as the breathability of the blankets used, whether  the foam is open or closed cell, how long one stays in bed and how compressed the mattress is when laying in it.

Preventing moisture from the body's respiration from getting into the mattress is an excellent solution if it does not compromise one's comfort.

I built my bed kind of like gp's.  Before I stapled on the cover, I stapled on a waterproof mattress pad which is a thick pad with a soft layer of plastic underneath.

I also wrapped my seat cushions with the waterproof mattress cover before I put the seat covers on.

I have not had the slightest hint of condensation under my bed or cushions in over a year.

The key is to keep moisture from getting into the mattress into the first place.
Pages: 1 2 3 4