Has this happened to you? You buy a vintage travel trailer, all excited. You get it home, pull back the cushions (which you should have done before handing over the cash), and you see something like this:
Rotten, warped, mildew-stained paneling, indicative of water damage.
If you're a newbie, you may be tempted to paint over it, put the cushions back in place, and call it good. Or to tack another piece of paneling over the bad spot. These may be cosmetic solutions. But they aren't safe solutions. And here's why:
What you have here is the trailer equivalent of Stage 4 cancer. Left untreated, the prognosis is poor-to-deadly. For moisture to have reached the interior wood, it first must have penetrated the seals on the exterior metal skin. Then the moisture attacks the wooden framing that gives the trailer its shape and structure, eventually rendering it structurally unsound.
Only after that does moisture reach and begin to rot the paneling. See the broader expanses of the horizontal wood, above? That's the back side of the paneling--the same paneling you see on the inside. The paneling itself is only a quarter-inch thick. That, some thin insulation, and the exterior skin, are all that stand between you--the owner/occupant--and the forces of traffic and nature. If you don't fix this problem, it will only spread and get worse.
Because it occurs from the outside in, that's how you have to fix it to do it right. In other words, you have to take the trailer apart from the outside, remove the bad wood, replace it, and put the trailer back together.
To do that, you first must remove the J-rail. This is the aluminum trim that wraps around the edges of the exterior.
The lights, windows, and license plate holder also have to come off. This is so you can loosen and either lift or remove the corresponding section of metal skin.
The old insulation also needs to go. As long as you're in there, you might as well replace it anyway.
Now you can start to assess the rot and take inventory of what will need replacing.
A side panel (maybe more than one) may need to come off in order for you to have best access to the repair areas.
Here's a close-up of a rotted rear corner support. It fell apart to the touch, as did much of the other rotten wood. This isn't what you want to have between you and the outside world as you're going down the freeway. One bump or pothole, and the back corner could collapse.
The actual repair phase of this trailer is about to begin. Check back for photos of the process.