Question about seams in aluminum trailer skin

[Johnny]

These streaks keep appearing on the sides and back of my 26BH. I've washed them off and before long there they are again.

I've already painstakingly siliconed the seams on the front of the trailer because I've heard that some folks have problems with water getting in when driving in heavy rain.

Do you think it would cause any problems to just seal all of the seams over the entire camper? I think that if I cleaned it, dried it and gave it a day in this baking sun to evaporate any water still in the seams, then use silicone to seal every seam then I wouldn't have these streaking problems.

[Marcm157]

Typically the black streaks come from the roof. I get them on my aluminum skinned trailer too. They are definitely a pain to keep clean.

[spoon059]

Highly doubt water is getting in through your aluminum siding. The water would have to make several turns to work its way into the bent joint. You are FAR more likely to have water intrusion from the roof to wall joint.

Those streaks are called "black streaks". Google it, they are a common phenomenon with rubber roof trailers. Not entirely certain what causes it, but it has to do with the natural oxidation process of the rubber roofing material. All the caulk in the world won't fix it. You have to cover it or clean it to get rid of the black streaks.

[Murff]

A good car wax will help the next time you have to wash them off!

Murff

[Crabman]

Never heard of anyone caulking those joints in the siding, could do more harm then good if moisture/condensation gets trapped in there. Black streaks usually come from the roof materials.

[Sundancer330]

Don't caulk those seems, the siding expands and contracts just like a house, if you do try to seal you will have a nice mess on your hands, as others said the water won't run uphill. The black streaks are from dirt on the roof that runs down the side during rain.

[Iraqvet05]

Keep your roof clean will help cut down on the streaks but they will never go away. I used Awesome Orange to get rid of the hard to clean ones but it removes the wax off the trailer. Meguires car wash is pretty good at removing the lighter ones.