To be fair, the internal frame of the upper structure is steel. http://i.imgur.com/JLIlRf3.jpg http://media.details.com/photos/5637e54e62b3b75f2bb3e531/mas...

Isn't it a little strange to be comparing plywood with 3" teak? Can you even get sheets of teak that aren't a veneer? Wouldn't LVLs or glulams be a more apt comparison?