Thanks for the warning, Billy. So what can we growers do about it? I've heard of ice dams forming if your rain gutters get blocked in Winter, but thought if they're working, then you don't have to worry. (That's all I've heard about the subject, from the guy who put my roof on.)
Luckily, the vent is closer to the middle of the house, so the roof is high above the room's ceiling. I'll have to look outside tomorrow to see if any snow is melting up there. I hope I don't have to pay someone to route my grow room ducting up to a roof vent or chimney or something. I appreciate the heads-up, bro.