3 feet of snow! I doubt it, but I don't have to worry about it either. Like I said it doesn't have to be flat, but it doesn't have to be complicated either. If I worried about it more I would give it some slope, but I'm able to hunt for a grand total of 32 days so it just wasn't worth the effort for me. I think I could get away with a flat roof with some simple design changes thought. The reason I say that is that my blinds are rectangular (roughly 4' x 6') so I have less of a span to support under that weight. I also like smaller but more windows.