Bumper Leak

In the process of tearing apart and remodeling my Sovereign (and Caravel, and Ovelander–every 70′s Airstream, I’m sure), I came across a very poor design issue. The horizontal piece of aluminum that the bumper locker door attaches to runs under the rear inch or so of the floor. Any rain or other source of water that falls in the bumper area will run under the plywood and rot it.

I recommend undoing the lower belt so that you can gain access to this area, then apply a bead of Vulkem at the interface between the lower edge of the exposed floor and the horizontal aluminum strip. If your skin doesn’t come down so low that you can’t, I’d coat the entire vertical edge of the exposed floor.

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As part of the “banana skin repair–dents” thread, I finally got around to sealing the bumper deck. Just as suspected, a lot of the flooring there is soft. I’m going to have to leave that for another day.

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I didn’t want to seal the entire height of the flooring, just create about a 1/4″ high dam to prevent rain water that sits on the bumper deck from seeping under the floor.

You CAN’T fix this by putting vulkem above and below the trim belt. All you’d do is create a tunnel where the water would have difficulty getting out or evaporating. You could put a line of vulkem at the top of the trim belt to keep the area a little drier and prevent some wicking into the flooring, but I’m not going to do that–I want as big a path as possible for water to escape.

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wacnstac: the thing that puzzles me is the problem could have been prevented if the small horizontal skin that the bumper locker lid is hinged to was eliminated–just carry the shell skin down another 2 inches and attach the hinge to the vertical skin with a thin standoff so the lid can open up flush with the shell. simple. Oops, before I say “simple” maybe I ought to go look and see if the frame cross member allows this. I think it does. As a matter of fact, I’m getting an idea…vhord: If you put your new “L” under the outer shell skin and it hangs over the bumper locker, all water should drain away from the floor and instead go into the bumper. I would think a bit about the bead of vulkem–it isn’t necessary to stop water migration, except capillary action between the skin and your “L”.

My rules about water control are:
1. First priority is to always allow a path for water to exit.
2. Second priority is to prevent water entry.This is precisely why the belly pan should not be sealed–you can attempt to 100% prevent water entry, but if you do that you almost guarantee that if any water gets in, it will be in there for a long long time. That’s a much worse situation than providing some method for draining and rapid drying (eg, air flow, no matter how slight).

So I think your “L” is a very good idea–it directs the water away from the floor, but doesn’t seal the area. The vulkem may also be a good idea–preventing capillary wetting of the skin may outweigh the danger of trapping water behind the skin. Don’t know.

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