Sealing plywood under Aluminium

[andy2]

Im at the stage of putting on the aluminium outer skin on the roof and im wondering if I should seal the plywood underneath first?

If so what with?
Thanks
Andy

[tony.latham]

Im at the stage of putting on the aluminium outer skin on the roof and im wondering if I should seal the plywood underneath first?

If so what with?
Thanks
Andy

Andy:

Water is the bane of camp trailers. I had a Hunter commercial built teardrop for ten years. (I think Lil Guy bought them out and created their Silver Shadow line) It had water issues that I finally chased down and fixed.

I use Raka epoxy. Their thin resin. It soaks into the top 1/16" of plywood and plasticizes it. Some use several coats of poyurethane thinned down 50% with mineral spirits. I think they call it "the mix". Some builders don't seal under the aluminum. Obviously I don't fall in that camp.

I just sealed my third hatch today.

Tony

[dmdc411]

I used up all my left over varnishes, thinned with mineral spirits. Yah the mix as its known. Then another coat of unique thinned, and a 3rd coat on the corners and around openings. Then I for the most part float my aluminum skins. They have sealer on laps joints, under all corner strips, and the rear hatch hurricane hinge. Otherwise the skins just "floats" as they say. Still haven't hit it with water yet!

[dmdc411]

Auto correct! It's supposed to say unthinned varnish. Not unique varnish. Haven't figured out all this smart phone yet!!

[andy2]

thanks, I went for the left over vanish option to!!

[angib]

There are some nice photos by bohemian of the old aluminum-skinned trailer he bought, which shows that aluminum is good for allowing water damage to spread un-noticed until the trailer suffers badly.



Not being able to see water damage is not better, indeed is probably worse, than seeing it and the idea that aluminum prevents water damage is very dangerous.