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RV Life Hack: Stop Moisture & Mold Growth Under RV Mattress

Why Does Moisture Collect Under An RV Mattress?

Moisture is a big issue inside RVs, travel trailers, and 5th-wheels.

Full time Rvers run dehumidifiers and do everything they can to keep humidity levels low, but the RV mattress is often forgotten.

Everything else in the camper can be bone dry, but under the mattress could still be moist and may even have mold growing both on the mattress and the wood underneath.

Related Product: Keep the clothes in RV closets dry and mold free using Eva-Dry Rechargable Mini Dehumidifers (click to view on Amazon)

Why are mattresses in RVs so susceptible to moisture and mold growth?

Mattresses inside RVs, vans and even rooftop tents are laying on cold surfaces. When you sleep on your mattress, the warmth from your body heats it up.

Moisture from the air and your body starts to condensate and collect between the bottom of the warm mattress and the cold surface it’s laying on.

If not kept in check, you could quickly end up sleeping on a moldy mattress every night.

The mold will eventually damage the wood under your mattress and could eventually threaten your health.

Because of how damaging mold can be, it’s important to do what you can to help stop condensation and get airflow under your RV mattress.

Related: RV Condensation And 14 Ways To Prevent Mold In Your Trailer

3 Simple Ways To Prevent Moisture & Mold Under RV Mattresses

These are some easy ways to stop moisture from building up under your RV mattress and keep mold from growing.

I say RV but these methods can be used for other common places where moisture builds under mattresses like boats, vans, skoolies, tiny homes, and rooftop tents.

1. Air Out The RV Mattress

Perhaps the most simple way to keep moisture from building up under your RV mattress is to air it out by lifting it up and placing something under it.

You can use cans, step stools, basically whatever you can find that will support the weight of the RV mattress.

See Also: Best Small RV Dehumidifiers That Help Prevent Mold

If you have a fan or dehumidifier, you can place it near the mattress to suck out moisture or get air flowing.

We use both Fantastic Fans and Maxx Air fans to help extract some of the moisture in our RV.

If you are camping or living in a climate with very high humidity and rain, should do this every day.

Be sure to keep a close eye on it.

If a day of being aired out isn’t enough to get the bottom of the mattress and the wood base completely dry, you may have to incorporate some of these other methods as well.

Place cans under the RV mattress to lift it up. Then use a fan or dehumidifier to dry.
If you don’t want to place something under your RV mattress to air it out, getting an airflow pad like the one below is a fantastic option.

2. Insulate Under The Mattress

A budget-friendly way to prevent condensation is to use cardboard to insulate under your RV mattress.

Take one or two layers of cardboard and cover the entire area under it.

This will help lessen the temperature difference between the RV mattress and the cold wood underneath.

This method is an easy fix that will work well in moderately humid climates.

You should check the cardboard weekly to make sure there’s no moisture collecting.

You may need to replace it every year or so. Make sure you still air out under the mattress after cold rainy days.

3. Use An Under Mattress Airflow Pad

The best way to make sure no moisture ever builds up under your RV mattress and to help the airflow underneath it 24/7 is an anti-condensation ventilation mattress underlay.

Den-Dry Mattress Underlay

Den-Dry RV and boat under mattress pad - Queen

Check Price at Amazon

The Den-Dry Mattress Underlay is made with spun polymer and plastic.

The hard plastic makes strong weaves that can hold up an entire mattress, allowing for air to flow underneath, even when you are sleeping on it.

The benefits of something like this are permanent anti-condensation and constant airflow.

Even in hot humid climates, moisture won’t collect and mold will have a hard time growing.

When it’s been extra wet outside, just place a dehumidifier in the bedroom or point a fan towards the RV mattress to create even more airflow.

You won’t have to lift the mattress all the time to place cans underneath to elevate it.

Related: Do I Need To Run A Dehumidifier When The RV AC Is Running?

There are 3 sizes of underlay mats. There’s a twin size (click to view on Amazon) that measures 38″x74.5″ and can be used under a bunk bed in a boat or RV.

The queen size comes in two strips that are 39 inches by 60 inches.

A camper queen is usually 60″ wide and 74-80″ long. You can cut the mat down to size to fit any length of a queen mattress.

There is also a king mattress size (click to view on Amazon) which is 2 pieces that are 39″x70″.

These mats are very lightweight, even the king size is only 8 lbs.

The Den-Dry Mattress Underlay is going to be the most permanent, low maintenance solution for preventing nasty mold from growing underneath your mattress.

This mat is useful for more than just RV applications.

It works well in vans, rooftop tents, boats, and any other mattress or foam pad that has issues with condensation and moisture collection.

It also helps give mattresses and sleeping pads a little more spring, which can make them slightly more comfortable.

Click Here To See A Full Review & Installation Instructions For The Den-Dry Mattress Underlay

den dry mattress underlay keeping an rv mattress mold free
Den-Dry Mattress Underlay underneath an RV mattress keeping it dry and mold free.

Why Is Preventing Moisture Under An RV Mattress Important?

Mold is the silent killer. It can destroy almost anything in an RV, boat, van, tent, and even a home.

Mold can also cause health issues, including asthma if left in your living space for too long.

I’ve seen too many videos of moldy walls being torn out of trailers and moldy RV mattresses being thrown away to ignore the importance of keeping moisture out of RVs.

See Also: How Do I Stop My Clothes From Getting Damp In An RV Closet?

If you do just one of these 3 simple things, you will save yourself a lot of time and money in the long run.

What If My RV Mattress Is Already Moldy?

If you look under your RV mattress today and find that it’s covered in mold and the wood underneath has mold growing on it make sure you take it out of your RV right away.

If there are only a few spots of mold, you may be able to clean it all off and save the RV mattress.

To clean a slightly moldy mattress, start by vacuuming off all the loose dirt.

Then clean off all the mold and mildew by using a mixture of equal parts rubbing alcohol and water.

Once the mold is totally gone, rinse with warm water.

Then apply a mold killer like Concrobium Mold Control Spray (click to view on Amazon) to make sure every bit of the mold gets killed and prevented.

See Also: Best Indoor & Outdoor Weather Stations For Home and RV Use

If the mattress is too far gone, it’s better to throw it away and get a new one than risk more mold growth.

After taking care of the RV mattress, wash the moldy wood that was underneath it.

If you don’t get all the mold that’s growing on the board, it will grow back into the mattress.

If the board has become soft and damaged, you may need to replace it. Be sure to spray mold killing chemicals on the wood part as well.

Make sure everything is totally dry before putting the mattress back into the RV.

Have any more ideas for preventing and getting rid of moisture under RV mattresses? Leave a comment below.

by Jenni
Jenni grew up in a small town in Idaho. With a family that loves camping, she has been towing trailers since a very young age.

10 thoughts on “RV Life Hack: Stop Moisture & Mold Growth Under RV Mattress”

  1. The best way to revive moldy RV furnishings and mattress’s
    bag them is large airtight bag and activate some chlorine dioxide. I have used this product in my RV several times and it destroys mold. It is a gas, and you need to exercise some precaution in its use.

  2. I’m looking not for a cheaper solution to hypervent/plastic landscaping material, but a more environmentally friendly alternative. I’m wondering if ridged cork insulation with solid or channeled (for more air flow?) under the mattress would work.

  3. We use Dendry under our boat mattress and run a dehumidifier and still get condensation under the mattress. Definitely have to keep an eye on it, even when using Dendry.

  4. I just read that you should take the plastic off your new RV trailer mattress, but should I leave the plastic underneath the mattress so there won’t be mold?

    • Hi John,

      The most important thing its to get some air under there so it stays dry. It think leaving the plastic might trap moisture inside the mattress.

      I would remove the plastic and either get a mattress underlay if you’re a full time RVer, or just make sure you lift the mattress to get some airflow underneath when it’s in storage.

  5. I need help. I sleep in my horse trailer and I want to put a mattress in the gooseneck. I bought a waterproof storage zipper bag to keep mattress in it so it doesn’t get dusty etc., but how do I deal with possibility of mold? Buy an air mat for under mattress and put it inside the storage bag? Or put it under storage bag between gooseneck floor and bag? Or both?


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