I'm not really a fan of those who do "roofing" though I can see why they want to do it. I just see it as too dangerous and potentially very consequential legally. Hell, I heard about a guy I know who went to the crane on the Grand Park II building and snuck on with other guys and he kept saying how he was shocked about how shaky the ladder was and that it was so windy on the crane. Not trying to offend any fans of it here, or start an online match of "you stink, no you stink worse", just my opinion of the whole "roofing" thing.
EDIT: I'm alright if one has permission to do that like an electrician or someone who asks management or whoever, but I mean people can lie about asking, it's not that foolproof saying you had permission sometimes.