Longevity of sealant and caulks

[GuitarPhotog]

Since my trailer is almost 65 years old, I look at everything I do to it with a view to the long term stability and/or reversability of my actions.

For example I'm hesitant to cut a hole in the all-aluminum roof for a ventilation fan when I don't have confidence in my ability to keep the installation weather tight for more than five years or so (the seeming life of caulking compounds I've used outdoors).

I've seen a lot of RTV applied to older (and some newer) RVs, trying to keep the vents and stacks etc. weatherproof. I know from experience that that's going to last only a year or two before it deteriorates to the point of failure.

So, what long-term solutions exist to weatherproof a metal-to-metal or plastic-to-metal joint?

<Chas>

[Shadow Catcher]

Chas
I don't think it is as much of a problem as you might think. Modern caulks and tapes are holding many things together. As an example the semi trailers you see with out rivets at the seams are held together with 3M VHB tape.
A number of the silicone caulks have a 20 year guarantee and while that is probably not a realistic expectation in many expectations sealing a simple hatch that can be easily inspected is not a problem.

[CARS]

So, what long-term solutions exist to weatherproof a metal-to-metal or plastic-to-metal joint?

<Chas>

When I think long-term, I look at the products I use in the automotive industry. Panel adhesives and seam sealers that stand up to 365 days a year out in the elements. Some of these products will be implemented on my build for joints that are never going to need service.

But, in the case of a vent or even door seals I have to think about someday replacing these items.

I could bond my Fantastic Vent to the roof so it wouldn't leak in a million years, but if a tree branch hits it and I have to replace it, I am going to take a section of ply off with it because it is bonded so well.

For my first tear, I am going to stick with what has worked for others. Butel and caulk.