Slightly random question about MDO

[Bart Sharp]

So obviously there's a difference between a waterproof structure and a water-resistant material. MDO is good for outdoor applications, but if I were to make a box out of it, seal up all the seams, and give it a good coat of paint, how much moisture would you expect to get inside if the box were out in a good hard rainstorm?

[Doug Shepard]

Well this one isnt totally sealed up it stays pretty dry even with the back window out and no flap on the door.
http://www.sawmillcreek.org/showpost...63&postcount=2
It's cheating a bit since the roof is rubber membrane but it's otherwise a box made of MDO on the outside, with a bit of cedar trim.