Where’s the Leak?


Senior Member
Nov 18, 2007
Portland OR
This one has me stumped.

With the top down and “fording” an atmospheric river for two days, no leak. So the usual suspect, the roof, seems to have an alibi.

Two nights of atmospheric river (with wind) with the top up, lots of water leaked in. But it doesn’t leak in light rain.

So I covered up a big part of the roof with tarps to try and isolate the source (I actually began covering more and more for various rainy days).
Left Front.jpgDrivers side.jpgInside.jpg

The water has always appeared in the front drivers side, as shown in the above photo (wet paper). In this photo, the camper was level front to back and lower on the drivers side. Camper has been generally level front to back. When level or a bit high on the passengers side, water is also across the front.The felt on the top of the border, at the seam, has always been damp.

The leak is really grounding us. Until I find it, I'll probably get a full size tarp to cover the roof so we can get out of Dodge. We don't suffer cabin fever, it's the metropolis fever that gets us.
Our 2007 Keystone has long had a small leak in the roof on the drivers side that very rarely shows after it rains. I have used 3M-4200 to seal all screw heads and seams on the roof.

On our Alaska trips we noticed that condensation and ice readily forms along the locations below the rectangular Aluminum ceiling framing tubes. It is my belief that our camper does not have any foam insulation in the hollow portions of the Aluminum tubing

I have long suspected condensation inside the Aluminum frame member that slowly collects then leaks out through one of the staple holes holding the ceiling trim up is causing the issue. Alternatively, there may be a small leak in a different location toward the aft end of the camper roof that is leaking into that particular fame tube but I have sealed everything I can find on the roof with 3M-4200. I cannot explain why no other spot has the same issue.

The use of Froli springs has eliminated any mold growth issues since air can flow around the mattress and it dries out - even with the top down - we live on the Central Coast of California so most of the time it is dry here. Even if the mattress and ceiling get wet for a few days it dries out and is is not wet long enough to support mold growth. However the lift panel on the left side has started to degrade from periodically becoming damp - the leak is small and it takes a half hour or more for water to drip into even a small puddle when the mattress is removed. I do remove the mattress when we close up the camper for extended periods to mitigate any risk of the mattress getting wet.
Thank you for the information. We live in the PNW and I suspect that we will frequently be dealing with moisture problems. We take delivery of a new Grandby next month. You mentioned the Froli system; would you be willing to share a few photos of your FWC Froli installation?

Thank you
Love that visual of "fording" an atmospheric river! We did the same thing in January/February... lots of moisture inside and under the mattress. We visited Marty at ATC and he promptly went to town (without being asked) to address the moisture )I hesitate to call it a leak when there is no obvious source... )

Biggest thing MIGHT have been what Marty calls the "Miracle Bead" of silicon on the upper part of the black trim around the front of the camper. He says that will deal with 95% of our issues. He might be right. We never encountered atmospheric rivers like that again, but plenty of rain on our trip since then and no moisture inside.
Thanks to everyone for the suggestions. I've wondered if the leak could be along the black trim - it gets covered by the roof overhang when the top is down. I'll run a bead of caulk along it and hope that's the answer.

After caulking the top and bottom of the top rubber strip and the seam just above the bottom of the bottom rubber strip, no more leak.
Sounds like Marty's "miracle bead" did the trick for you then, except that you ran three of them. I'm likely going to do the same!
I learned a new technique for finding leaks recently in one of my boating forums.

The flat tire method!

Close up everything, rub some soapy water on suspect areas, go inside with a leaf blower or shop vac on blow. Have someone outside looking for bubbles.

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