
Moisture buildup is one of the biggest challenges of full-time RV living, especially when it comes to your mattress. Condensation and trapped humidity can lead to mold and mildew growth, which can damage your bedding and pose health risks. The Den-Dry Mattress Underlay offers a simple yet effective solution to this problem by improving air circulation under your mattress.
What is Den-Dry?
Den-Dry is a breathable mattress underlay designed to prevent moisture buildup and improve airflow beneath your mattress. It consists of a durable polymer mesh that lifts the mattress slightly off the bed platform, allowing air to circulate and moisture to dissipate. This design helps reduce the risk of mold, mildew, and musty odors, which are common issues in RVs where ventilation can be limited.
Key Features
- Moisture Prevention – The open-weave structure promotes airflow, preventing condensation from getting trapped under your mattress.
- Durable & Lightweight – Made from strong, flexible polymer that is thin and unnoticeable.
- Easy to Cut & Customize – Can be rolled out and trimmed to fit different mattress sizes and shapes. We purchased two queen sizes, one for our bed and then cut the other in half for the boys narrow twin bunks.
- Silent & Non-Slip – Unlike some other moisture barriers, Den-Dry doesn’t crinkle or shift around during sleep. Honestly, you won’t even notice it’s there!
- Low Maintenance – Simply lift the mattress and wipe down occasionally for easy cleaning.
Our Experience: Using Den-Dry to Prevent Mold in Our RV as Full-Timers
We’ve used the Den-Dry Mattress Underlay since the start of our full-time RV journey over two and a half years ago, and only recently has it started to show wear. Some sections of the mesh have become crushed, primarily in areas where we sit frequently, like the corners (see below photo). However, every time we check, it’s still effectively preventing mold buildup. Even with its high price for a thin mat, the investment is well worth it to protect your mattress and RV from moisture damage.

Where to Buy
The Den-Dry Mattress Underlay has been available online through retailers like Amazon and specialty RV supply stores. Or check them out here on their website. However, due to its popularity and positive reviews, it has become difficult to find in stock.
Sizes and Pricing
Twin/Twin XL Underlay:
• Measures 39″W x 75″L
• Fits a twin bed
• 3″ flap for joining multiple panels
• Cost: $99.99
Queen Underlay:
•Fits a queen or full bed
•Measures 39″W x 120″L (makes two 60″ wide strips)
• 3″ flap for joining multiple panels
• Cost: $119.99
King Underlay:
• Measures 39″W x 160″L (makes two 80″ long strips)
• Fits a king bed
• 3″ flap for joining multiple panels
• Cost: $139.99
Similar Products
Given the scarcity of Den-Dry, you may want to consider alternative solutions if you’re unable to wait for availability. One comparable option is the DRICORE DuraDri Mattress Underlay, which offers similar moisture prevention benefits and is available in king, queen, and twin sizes.
In Conclusion
Incorporating the Den-Dry Mattress Underlay into your RV setup is a simple yet effective way to prevent mold, extend the life of your mattress, and protect the wood in your RV from moisture damage. Its ability to improve airflow and adapt to different climates makes it a must-have for full-time RVers. With easy installation and minimal maintenance, it’s a smart investment for a healthier and more comfortable sleep on the road.
While on the topic of RV bedding and mattresses:
What you need to know about upgrading your RV mattress