I'm looking to put corrugated steel sheets on a roof and have some questions. I'm very familar with putting steel on, so thats no problem, my questions lie more with the vents. Any advice on how to waterproof around sewer vents, roof vents & steel chimneys would be great. What do you do when these things fall into one of the ribs on the steel? Any advice or links to websites would be great, thank you.