"Gary Warner" wrote in message
...
My question today is: There are parts of the trailer that are boxed in.
This
means that paint won't get down in there. But water still will. The
water
will drain out.


Obviously it won't be seen, so it doesn't have to look pretty.



A significant advantage to using channel instead of box frame members is
that you can paint all surfaces of the channel.

I had a trailer that had one section made of box. The trailer was already
old and rusty when I got it, and I spent a lot of time repairing it,
sandblasting and painting. The trailer looked great, for a while.

The welds connecting the box section were not water tight, which allowed
water to get in. Then rusty water leaked out. The rusty water trickled
down the painted surface and left ugly rust stains behind.

If you can seal those boxed in areas you will be a lot better off. If you
can't weld them shut you might want to consider filling the box with a
closed cell expanding foam. Evercoat makes a one-component urethane foam in
an aerosol can that you can inject into small spaces. This is a closed cell
foam that is water proof. You may have to drill a few 1/4" holes in order
to get the foam in and air out.

Rod