Minor, i hope, cabover water damage.

[chefdc1]

We were just out in the MH (1997 Damon Hornet) prepping to do some painting, when my wife decided to pull the sheets off in the cabover. That's when she noticed moisture. It had previously been bone dry. We had some heavy rains a few days ago, so somehow, water made its way in. The bottom of the mattress cover was wet, as well as the foam. Not soaked, but wet. The wood underneath is also wet, but definitely not rotting through...yet. The wall to the left of the front window also seems less than perfect. I pried up the wood a little and the Styrofoam underneath is also damp.
Obviously, my first step is to find, and stop the leak. I'm assuming it's coming from the front window. The caulk around it does not look perfect. It's dark now, so I will examine a lot more in the morning.
Okay, now are the beginning of my many questions:
Assuming the leak is around the window, what type of caulking should I use?
How difficult is it to pull the ply up, replace the styrofoam and plywood?
How difficult to pull the front inside panel around the window?
Nothing is rotted through, so I think we're catching the problem early.

[BFlinn181]

Don't use silicone. It will fail and getting any other caulk to stick will be impossible with the silicone residue. This is a pretty good product:
ProFlex RV Flexible Sealant - Clear - Geocel 28100 - Roof Maintenance & Repair - Camping World

Scrape and cut away as much of the old, failed caulk as possible. If you want a neat job, be sure to use masking tape to limit the boundary of where the goes.

You could take the inside window flange off, usually held on by lots of screws, and take the window out to really make sure it's bedded properly. That would also ensure the sideway isn't damaged too much since it's usually trapped under the inside flange. If removing the window, I'd use the butyl rubber strip caulk that was probably originally used.

I wouldn't think the styrofoam insulation needs replacing unless you discover mold or rotten wood. Rotted wood must be replaced, if not, it will just continue to spread, even if the water source is eliminated.

[chefdc1]

Did a lot of digging around today...lots of rot! I'm going to have to rebuild the entire cabover bed. I think I tracked the leak(s) to the front seams. I cleared out all of the caulk on both sides of the trim, from roof all the way around, under cabover and back to house. Started getting dark so I couldn't reseal, but I covered everything with duct tape. I completely dried where the water looked to be coming in. I'm hoping that everything is still dry in the morning. There is supposed to be a shower so it should be a good test.
The plan is to reseal everything with a flexible, waterproof, non silicone caulk (DAP Clear). Now I'm wondering if I need to pull off the strip in the trim to check the screws.
Also, can I seal along the strip (inside the trim) with flexible caulk as well?
Should I be thinking about using eternabond, and if so, where? Under the trim? Over the trim?

[BFlinn181]

Eternabond is great for seams and long time cover. Butyl rubber strip is typically used for bedding windows and trim, it will seal around screws.
Amazon.com: Dicor (BT-1834-1) 1/8" x 3/4" x 40' Butyl Seal Tape: Automotive

I suggest you also re-caulk the ICC lights probably on the nose of your RV, they are famous for leaking.

[jdoran1973]

I am a huge fan of eternabond tape.used it on a lot of the Rv seals. Pricy, but worth it

[2500HD]

Proflex is the best caulk to use on a job like this it is flexible and lasts for years.

[chefdc1]

For now, just going to duct tape it up. Waiting for some warmer weather to pull out the cabover floor and start the rebuild. When done, I am going to seal everything...with everything! No more leaks!!!!