Corrosion on the Roof!

Remember in April, back in St Augustine, when I said I thought the last of the leaks had been nailed? Well, I was wrong.

Turns out we still had one small leak ... somewhere. It only showed up in heavy rain, but while sitting here in Vermont and in New York at GSM, we'd see a bit of water. One day, when the trailer was parked slightly off-center, the water appeared in the bedroom closet near the wheelwell (where we've since replaced a piece of floor). Another day, the water dripped from the rear Fantastic Vent. Another day, while towing to Plattsburgh, rain dripped in through the front Fantastic Vent.

It was always somewhere different. So we knew it was getting in somewhere up high, and traveling through the roof until it found an exit point. The exit point changed depending on which way the trailer was tilted.

So Colin went up last weekend to take a look. First off, he found that we may have had a bad batch of Vulkem. In certain places, the Vulkem shrank and gapped open, which it normally doesn't do. This left potential leak points around the Fantastic Vents and the air conditioner. But we weren't convinced that these little gaps were the cause.

Then today Colin went up again, this time eyeing where the old Skyliner antenna used to mount on the center of the roof, just forward of the air conditioner. Here's what he saw:



Note the generally scuzzy condition of the roof metal. The paint has completely failed as a result of years in the Florida sun, and there's oxidization and other "stuff" up there as well. A circular remainder of caulk seems to cover something, but what?

The finger in the picture is indicating a pair of former rivet holes which were undoubtedly part of what held on the old antenna. Those need to be caulked and riveted shut.

But that's not the end of the story. Colin decided the metal looked a bit suspicious and took an air-powered wire brush to it, in an attempt to clean up the oxidization, remove the caulk, and get a better look. Here's what he found:



Lo and behold, there's an entire pattern of rivet holes! But they were mostly covered with caulk, so they weren't the problem either.

But that's still not the end of the story. Colin noticed the metal was actually pitted. What caused that? Apparently, dissimilar metal corrosion between the base of the antenna and the aluminum roof. Without a gasket to separate the two, in the salt air environment near Cape Coral, Florida, the pot metal of the antenna was eating the roof!



See the deep pitting? A bit more wire-brushing on that weakened aluminum, revealed a startling thing: not only deep pits, but complete holes! This aluminum had the integrity of rice paper.

And here is what he ended up with:



Obviously a big patch is going on the spot where the old antenna used to sit. So here's a lesson for you, if you've got an old Skyliner antenna on your vintage trailer. Dissimilar metal corrosion can be a problem. If you've got a mystery leak, check it out!