Phantom Leak in Bedroom Slide

[Wmass camper]

We have a 2019 Montana High County 330 RL. When the bedroom slide is out, we are experiencing a small amount of water accumulating in the underbelly just under where the head of the bed sits.
Both windows have been recaulked, and also along the bottom edges of the slide. Roof has been checked with no visual issues near that site. The inside of the RV is entirely dry. At this point in time we have no idea where the leak is. Has anyone experienced anything similar and have any advice as to what the culprit might be. Or how to trouble shoot such a phantom leak?

[rohrmann]

Sounds like a plumbing leak. This could be a loose fitting on any of the fittings including possibly the black tank flush line where it connects to the tank. Another worse possibility could be a leaking tank. Not sure how rain could enter the belly area.

[newowneroldmontana]

Hi Wmass camper--I lived in Holyoke for a little while, way back when! (Waaay back when.)

I have had water accumulate in the underbelly before, when my grey water tank got too full and overflowed. Could you have a grey water tank problem?

[newowneroldmontana]

Oh, never mind--what I said doesn't make any sense. You're not talking about underneath the camper. I bet there's a leak somewhere along the top of the slide, though, where the top meets the outer wall--or water could be getting in on the side, around a screw.

[Daryles]

Recaulk along the outer edge "frame" of the slide. On another forum someone posted their leak was along this edge. Rotted out the floor before they discovered it.

[Mikendebbie]

Looks like there is no plumbing near the bed slide…so the only way water could enter the space between the plastic bottom sheet and the plywood slide floor would be…
1. Somewhere along one or both of the bottom slide trim angles
2. One or both of the windows
3. The trim piece that anchors the roof membrane on either side of the slide (probably not likely).
Edit: I agree with Daryle’s post. That joint could leak.

You said you had recaulked the edge of the bottom angle trim. My money is on one of the windows. The window frame outside piece is set into butyl putty and tightened from the inside. There must be a small gap in the butyl putty. You could remove the window (both windows ???) and install new butyl tape the re-set the window frame.

OR you could put a bead of ProflexRV around the perimeter of the window frame. Normally as part of maintenance - folks here on the forum check that joint annually and touch it up as needed. Run a bead of Proflex over the top of the bottom trim angle. If you have previously used silicone at any of these joints - Proflex will not bond to silicone. Remove the silicone and clean it thoroughly before laying a bead of Proflex.

This YouTube video from AZ RV Expert will give you a good idea for how these slides go together. I think the floor plywood on this older Montana rotted from a leak thru the bottom trim angles. This is a screenshot not a link. Go to YouTube and search for the video.

[firestation12]

Our 2019 Alpine developed a leak in the area described. It was discovered to be coming from the top of the slide out. There is a row of screws just behind the outside face of the slide out. The row of screws have a 2” adhesive back tape covering the their semi round heads. I’d bet you have the same problem. Those screws have a habit of backing out which lifts the seam tape causing a leak.

[High5er]

This could be condensation. I know it sounds unlikely, but while we were getting our furnace repaired last week, the tech told us a story about a couple that had only been in their 5th wheel for a few months and had a bloated underbelly where there was no plumbing. He found that they weren't venting the moist air out and it ultimately resulted in condensation collecting in the ceiling and trickling down to the underbelly. If you can't find a void in the seals/caulking, this may be another possibility.

[Ahdmeyer]

I believe that firestation 12 may have your problem solved, i had the same issue of the screws on the slide top backing off and going through the tape. removed the screw and reset them then put new heavier tape they use on commercial roofs on top and problem solved

[laverdur]

This sounds similar to a problem I had. Your picture shows the bottom edge of the slide. On that edge is a strip of angle bracket. On my Monty there was no caulking along the top edge of the angle bracket. With the slide open, when it rained the carpet at the headboard would get wet. The solution in my case was to GENTLY pry the top edge of the bracket away from the fiberglass side wall and squirt a generous amount of silicone caulk into the space. I took it in small increments and used a small screwdriver to hold the bracket away from the fiberglass. When the small screwdriver was removed, the spring tension on the bracket allowed it to pull in close to the fiberglass and squeeze a little of the silicone out. A quick wipe with a wet finger removed the excess silicone and resulted in a good seal. No more problems with that in 6 years. Be very careful not to bend or distort the angle bracket or you could have more problems. Hope this helps.

[Thudly]

I had a leak that no one could find. I found it was the little doubled up rubber seal around the cable. I used contact cement to reattach it and the problem was solved.

[Wmass camper]

Thanks for your replies. We caulked around all the Windows and also the suggested trim on the side of the slide. All of it has alleviated the leak.