Quote Originally Posted by JamesR View Post
Have a look at marine ply.
Thats what I thought as well, but from the research that I did today, marine ply was more about its construction, as opposed to its out and out waterproofing capabilities. From what I have read, you still need to seal marine ply. I thought, that if this was the case, I might as well just use normal ply and make sure its well coated.