Thursday, September 21, 2023


We found water under the RV’s bunks. Will mildew paint take care of it?

Dear Dave, 
We found water inside a cubbyhole underneath the bunk beds. Underneath the rug was tile and under that we cut the tile and found water damage on the wood. We left a dehumidifier in there waiting for it to dry and then painted with mildew paint. Getting all the rugs out of there, using mildew paint on the floor, and then using throw rugs that we can take in and out every season. What do you think? —Eric, 2007 Chapman Wind River

Dear Eric,
You obviously have a leak coming from somewhere and you need to find out where that is. Otherwise, what you are attempting is a band-aid fix and it will get worse. Luckily, you found just a puddle of water, as usually it is not discovered until there is extreme damage. From the photo it looks like you caught it at an early stage. The procedure you are doing is fine, but let’s find the source of the leak.

Where leaks usually come from

Most visible water stains are not leaking at the point of the stain, rather somewhere higher up and traveling through hollow framework or between layers of sidewall material. The most common areas for moisture penetration that would show up at the floor level is a window, corner seal, or roof-to-sidewall seal.

Since this is under the bunk bed pedestal, I would start by looking for any window just above this area and check to make sure the butyl tape is good and there are no gaps. Most of the time you can push on the wall inside and out and feel if it is mushy or soft, which is an indication of moisture penetration. If that looks good, then inspect the corner trim where the sidewall meets the back or front panel.

Where water is likely entering this RV

I’m not familiar with this floorplan so I don’t know if the bunks are in the front or back. If they are in the front, the leak could be from driving in the rain. If they are in the back, it is most likely coming from the top down. In that case, you need to get on the roof and look at the sealant along the roof to sidewall, roof to back or front wall and any vents or other cutouts in the roof.

We recently worked on a 1996 Salem trailer that seemed to be in good shape other than an enormous amount of silicone covering the front driver’s side trim corner with hex head screws installed every 5 inches, which is not standard. After taking out the dinette in the front to do a DIY remodel, we found the floor to be rotten due to a massive leak. The leak started on the roof; however, the previous owner thought it was the corner and did a band-aid fix that did not solve the problem. The result was a new floor and stringers! So, it is important to catch it early if you can and fix the leak!

Windows are installed with a putty-type material, called butyl tape, placed between the window frame and the sidewall. It should be sufficient to seal it without the need for silicone. However, it can get brittle and pinch out, so it might be necessary to remove the window and reseal it. You can apply silicone designed for fiberglass around the edge, but it is best to R&R the butyl tape.

The roof-to-sidewall joint is typically a metal trim piece with self-leveling lap sealant covering it. This can also get dried out and create pinholes or cracks that will allow moisture to penetrate and run down the sidewall. If it is a small crack or pinhole, you can simply apply more sealant. However, the best fix is to use a heat gun on low setting and scrape off the old sealant with a plastic putty knife and reapply new sealant.

 You might also enjoy this from Dave 

How do I find what’s causing the water leak in my RV?

Dear Dave,
While city water is hooked up to my RV, the water starts to leak, causing the living room floor to leak. What could this be? —Jason, 2001 Tiffin Phaeton

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

Read more from Dave here


We have a popular forum for Ask Dave. Please be as brief as possible. Attach a photo or two if it might help Dave with his response. Click to visit Dave’s forum. Or send your inquiries to him using the form below.

Click or drag a file to this area to upload.


Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.



Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sign up for the

RVtravel Newsletter

Sign up and receive 3 FREE RV Checklists: Set-Up, Take-Down and Packing List.