"Rod McInnis" wrote in message
...

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

We used 5" channel for most of it. But the tongue & bow stop are
box. Plus the side had a *slight* bow in it which would 99% likely
have been fine, but we boxed in some of it with 5" flat stock. So
now we have another area we can't paint.


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.


Hmmm, interesting idea.

Thanks.