Mold and mildew can form on several RV surfaces such as the roof material, awnings, and exterior sidewalls. It can also be found inside cabinets, around the toilet, and shower stalls. The growth of mold and mildew is primarily influenced by 3 factors: moisture, warmth, and organic materials for them to feed on. It grows by tiny spores that start invisible and typically float through the air land on wet surfaces and then begin to grow and darken.
Here are some common ways mold and mildew can form on the interior of RVs:
High Humidity And Condensation
RVs are often exposed to high humidity levels, especially when used in areas with a lot of moisture, like when near lakes or rivers. The moisture in the air can condense on cool surfaces inside the RV, providing an ideal environment for mold and mildew to grow.
Water Leaks
Leaking roofs, windows, or plumbing can introduce water into the RV’s interior. If not promptly addressed, this moisture can accumulate in hidden areas, such as inside walls or under flooring, and lead to mold growth.
Poor Ventilation
Inadequate ventilation can also trap moisture inside the RV, especially in bathrooms and kitchens where steam and humidity are common. Proper ventilation, like using roof vents and opening windows, can help reduce moisture buildup. This is especially important during storage when condensation can occur with temperature changes.
Tips To Reduce Mold and Mildew On Interior Surfaces
Reduce interior moisture such as wet clothing, cooking, and condensation. Identify what might be adding moisture to the air such as showers, boiling water for cooking, and wet clothes or towels hanging in the bathroom. Make sure all surfaces are clean and dry such as shower curtains, and countertops, and don’t leave any items standing around wet such as dishes. Increase airflow with roof vents and fans, and use dehumidifiers such as damp rid or even portable units. Open cabinets and closet doors to allow more air circulation.
This winter I tried a renewable dehumidifier called H2Out in a Thor Challenger and it was outstanding. They have different sizes that cover anywhere from 25 sq ft to 900 sq ft and all you need to do is put them in an oven to dry out the proprietary beads.
We put a couple of the 600 sf models in the bedroom and a couple in the living room with the cabinets open and had no condensation and zero mold!
Exterior Mold
Mold represents a type of fungal growth that adheres to dirt on surfaces, and once it reaches the black stage, eradicating it becomes notably challenging. Furthermore, it has the potential to cause permanent staining on roofing materials, especially rubber membranes. This underscores the significance of not only periodically cleaning rubber membranes like TPO and EPDM but also conditioning them.
Since fiberglass roof material is flat, it is less likely to house dirt, dust, and moisture like the rubber membrane which has pockets and can produce a perfect environment for mold to form.
Preventative Maintenance
Periodically clean the roof with Dawn Dish Soap and water by parking the rig on a slanted driveway for moisture runoff. Make sure the ladder is at the back or high point so you can get down safely when done.
Put a ¼ cup of Dawn in a 5-gallon bucket of water and fill it with warm water. Have someone periodically spray down the sides of the rig so no chalk or dirt from the roof sticks to the sidewall and windows. Using a mop or foam brush on a stick, start at the front spray a 4’ corner with a hose, and mop it down. Rinse it off and move over to the right side. Doing this in 4’ sections and working your way to the back ensures you are always walking on dry material.
Removing Existing Mold
If your roof material already shows signs of mold and mildew buildup, I would first start by cleaning it with Dawn Dish Soap and if it needs more treatment, you can use a variety of products including over-the-counter bathroom products such as Tilex Mold Remover or Mold Armor. For years I have used a ¼ cup of bleach in 5 gallons of water and it has worked very well, however, some people claim bleach is not environmentally friendly and will harm the environment and sewer systems. I have worked with our local Department Of Natural Resources (DNR) and Sanitary District and they stated that 1/4 cup mixed in one gallon of water and then diluted by 15 gallons of water would not affect a septic system. It would need to be 3/4 cup in every gallon to qualify as too powerful a solution.
I have also used Trisodium Phosphate (TSP) found in the paint section of home improvement stores, however, several states have banned this product but I do see TSP alternatives.
Awnings
Another exterior material that can develop mold and mildew is the vinyl and acrylic fabric used in awnings. Once again, the mold is attaching to dirt, dust, and moisture on the material, not the material itself so it is important to periodically clean the awning material as well using the same Dawn Dish Soap. The main culprit when it comes to awnings and mold is rolling the awning up when it is wet, or letting it sit out long enough to develop condensation. Periodically cleaning and letting it dry completely is the best way to prevent mold and mildew on awning fabric.
Remember, keeping your RV mold and mildew-free is not only about maintaining a comfortable and healthy living environment but also ensuring the longevity of your RV’s materials. By taking these preventive measures and addressing issues promptly, you can enjoy your RV adventures with peace of mind and a clean, mold-free space. Happy RVing!
About the author: Dave Solberg: Managing Editor, RV Repair Club
For the last 25 years, Dave has conducted RV maintenance and safety seminars, developed dealer and owner training programs, written RV safety and handyman articles authored an RV handbook reference guide, and logged over 100,000 miles on the road in an RV.
RV Repair Club is your go-to online resource for enthusiasts who want quality RV maintenance, repair and upgrade information – a community where passionate RVers can come together to gather knowledge and share their experiences.
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