Bad Window Seal?

Bad window seals in RVs are a common headache—here’s how we approach them differently than residential window replacement projects:

1. Diagnose First
   • Tape plastic over the suspect window overnight – if condensation forms between plastic and glass, the seal is failed
   • Check for butyl tape ‘ooze’ around the exterior flange
2. Temporary Fix
   • Clean channel with RV-grade silicone remover (never acetone!)
   • Apply CRL 1816 sealant (stays flexible in temperature swings)
3. Permanent Repair
   • Full gasket replacement requires removing the interior trim panel
   • Upgrade to ‘Thermalock’ gaskets (lasts 3x longer than OEM)

We recently restored a 2015 Winnebago at Aurora’s RV Medic where resealing all windows reduced interior noise by 40%. The ‘Mobile Seal Solutions’ guide at DNG Service shows our cross-section technique for preserving aluminum frames. Pro tip: Always reseal in 60°F+ weather—cold curing compromises adhesion!

I had the same problem with one of my windows on my 5er.  I used the same stuff I use on the side of the RV (Lexel sealant).  However, I later found a pin hole on the edge of my roof where the water was coming in and repaired that with Dicor.  No leak any more and a reinforced window.  If you are getting a leak at window go from top to sides about 4" down.  No need to do the entire frame.

I ruined my last truck camper by using caulk to not seal a leaking window. It continued to leak inside the wall and rotted the floor. Remove the window, clean the old butyl tape and caulk off, and reset with new butyl tape.

Are you sure it's coming from the window? Could be the roof. Every year I re caulk all seams on the roof, windows, corners etc, with the appropriate Dicor. 

Dicor Lap Sealant, probably the “no sag” line. The other possibility is to take the window out and reset it using butyl tape sealant.