Right, and that's probably exactly what happened... the real problem is that my ducks are gross, and I can't seem to figure out a food/water distribution system that they don't turn into some sort of slimy slip-and-slide.
Maybe, but a roof is a very different situation than a duck coop - roofs are designed so that the water runs off. They don't have wet bedding sitting on top of them.
I think it would have been fine in the chicken coop.