Installing new vinyl trim inserts, caulk or no caulk?

Question

So I replaced/repaired my roof this summer on our hybrid travel trailer,  and as part of that headache, I replaced some of my aluminum trim pieces along with all new white vinyl inserts and #10 screws.  Obviously, the vinyl insert is NOT waterproof, but I have heard several folks mention that it waterproofs the trim and not to skip that step.  In my opinion, the loose-fitting vinyl insert was never designed to be waterproof and is really just for aesthetics to hide the screw heads.  During disassembly, I did find a lot of evidence of water that had gotten behind my old vinyl trim inserts.  Subsequently, many of my trim screws were heavily rusted, which may be because of trapped water behind the vinyl trim.  Just an assumption, but the water had to have been getting in somewhere to rust so many screws.  I found two spots where the roof was leaking when I removed my old rubber roof but hard to say if that's what caused the trim screws to rust or perhaps water trapped behind the vinyl insert trim.  So for installing new vinyl trim inserts, I've seen some YouTubers caulk both edges where the insert goes into the trim channel and was wondering what the school of thought is out there in the community.  To caulk or not to caulk?

mfl · Answer

No need to caulk vinyl. When replacing rusted screws, that is the time to put a dab of caulk/sealant on the new screws, prior to snugging them.Jerry

ladyrver · Answer

I did what MFL did when I replaced the vinyl trim.  New stainless steel screws with a dab of caulk before tightening them down.

mro2009 · Answer

There is new butyl tape behind every piece of trim that was removed and replaced.  And all new screws were used in the rebuild which is already complete.  It doesn't make sense to back each screw out to add a dab of caulk and retighten them all.  But thanks for the suggestion.

fj12ryder · Answer

I just replaced the vinyl on our Momentum, and didn't use any caulking.

brucemc · Answer

Note that vinyl shrinks with age. As many other report, the arch just above/behind the drivers/passenger doors on Class C's pull out over time due to this shrinkage.
Rather than replace the length, I pull it up from the bottom, then add a small piece below to complete the fill, like this:

The small piece was a tad narrower, so it didn't bulge out like the original, but still did the trick. I added an external stainless screw to hold everything in place.

As others report, seal each screw head before inserting the vinyl strip

For those of us who use our rig occasionally over the year, a big part of preservation is storing your RV under a solid cover or in a garage/shop to keep it out of the elements. It's not possible for many folks, but it sure makes them last a lot longer.

Forum Discussion

Installing new vinyl trim inserts, caulk or no caulk?

About RV Tips & Tricks

Related Content

Insert pins

Truck Camper A/C instalation

Easy way to install vinyl trim insert

Installing new vinyl trim insert at the roof line

Talon Inserts with steel Torklift Receivers