Rear roof Water Leak

[govmanbob]

We have a water leak in our 27 RSB overhead bed cabinet area that looks like it came from the roof seam that runs across the rear of the roof from side to side on the coach. We have not had this issue previously however the coach is parked in our driveway at a slight incline so I imagine when it rains the water is running toward the rear of the roof. I got up on the roof and looked over the seam and now it is dry and I don't see any existing caulk.
Wondering if anyone else has had this issue and is caulking the seam the right fix? If it is what caulk or material did you utilize?

20230816_140127.jpg (63 KiB) Viewed 1042 times

[SeaKing1]

From the owners manual:

DAE35E81-5D70-477A-8CC6-2D728797BCC0.jpeg (134.52 KiB) Viewed 1005 times

[SteveLombardi]

https://youtu.be/zmVzjGTa5m4

Dear SeaKing1,

Please see attached video of my 2012 25RB. I pressurized the interior compartment and put soapy water on the outside. I did this after I noticed water leaking through the ceiling near the rear steel safety roll bar. The motorhome was 2 years old at the time so the factory fixed it for me. I do know that the vinyl strip must be removed to get to the over lapping joint that mates the rear cap and the roof together. I also know that the vinyl strip is not available so it must be reused. It is held on with 3M VHB (very high bond) 2 sided tape. I was told that the screw fasteners that are revealed when the strip is removed must be tightened and/or replaced as well as the old sealant dug out and resealed.

As a side note I also found some minor leaks at the side marker lights at the rear. I'm thinking they must have had the new guy working at the factory that day.

To pressurize the interior I closed up everything, roof vents, tape over drains, all windows ,outside compartments closed etc. Turn on dash air full blast in the mode where it draws air from outside and with this you might get enough pressure to do the test. You will know when you try to close the passage door and you feel the air rushing out. I added an extra source of air by using a shop vacuum's blowing side and coupled into a Styrofoam board I cut to fit one of the outside storage doors. Don't use the ceiling vents to add pressure. They won't help. Any questions...just ask.

Steve L.

[SeaKing1]

Brilliant idea to pressurize the coach and look for leaks.
I tried watching the video but notice said it was private.
Did you get on the roof and clean well around any plumbing vents, fans, and ladder mounts?
Were you able to re-seal/caulk and achieve a good result?

[SteveLombardi]

https://youtu.be/zmVzjGTa5m4

I made the video public so hopefully you can see it now.

There is a commercial machine some rv repair shops use to pressurize the interior. I got my idea from them and from some others that I have seen on the internet.

I have never re-sealed the vents, luggage rack, ladder mounts etc because they can be readily seen and have never looked suspect. It was the leak coming from behind the white vinyl strip that leaked and it was letting quite a bit of water in when I was parked in a position for it to flow into the seam. I had gathered nearly a cupful in one rainstorm.

I did not make the repair myself but I know how the seam is constructed. It is two fiberglass overlapping surfaces with an adhesive-sealant between them. Through the seam are screws that screw into the plywood panel that is bonded to the underside of the roof section. note: the rear fiberglass cap lays on top of the roof fiberglass surface. To make the repair the screws were loosened slightly to allow the old adhesive in the seam to be dug out and new put in. Then the screws were tightened and or replaced if not gripping tightly. The hard part will be dealing with the vinyl strip that had to be re-used. The old two sided tape must be removed and replaced with new and then the strip re-adhered over the seam. After the repair I actually went a little farther on my own and laid a bead of caulk along both sides of the vinyl strip to make sure it was reattached strongly and would resist leaking. I used 3M 5200 sealant which is super strong and some might say will make it impossible to remove if needed in the future. The 5200 sealant worked so well that I eventually went around the entire coach and sealed the edge of all the vinyl strips hoping to keep moisture away from the 2 side tape underneath. This was all done 7 years ago and it is all still good.

Hope this helps, Steve

[Tahoe]

I've had 2 frustrating leaks, one in front and one in back. The rear one became obvious when inspecting along the seam and I could see a missmatch in height in one area. I decided to use 4 inch wide Eternabond tape over the entire top seam. That wa approx 6 years ago and it hasn't leaked since. In the front I had a horrible le a k on the drivers side verticle seam about 2 feet down from the top. I ended up removing the side seal and found a a 1/4" dia hole/ gap under the seal. Mg fix was to stuff fiberglass mat in the gap, then some epoxy. After letting it cure I reinstalled the seal and recauked. Holding so far, but the leak was so bad we had to remove all the carpet which meant removing everything attached to the floor. I replaced the carpet with cork flooring which looks as good as the day we installed it. Leaks can be very hard to trace sometimes as it can travel some unlikely paths sometimes. It's the only major issue to date on our BF. Oh wait, we had a front overhead window leak, but very minor and that was fixed with glass sealant and some caulking.

[deshet]

Did you take any pictures of the setup you used to pressurize the RV? Would you please post them. I am surprised that they are so air tight.

Thank you

[SeaKing1]

I went on the BF Facebook group and found this information you asked about:

https://www.facebook.com/groups/3048763 ... 075811714/

Hopefully this will help.