They are built pretty well. I bought one second hand 2 years ago and used it for a year to store my car outside while I was building a new garage. It worked well and even handled the snow load well (although last winter here in VT was not that bad). I'd just go out after (and sometimes during) a snow storm and clear off the top using a push broom like a snow rake. I would suggest installing a vent however. I did not but instead just relied on descent packs. My car, that was already crusty came out even worse. You could make one yourself, or shelterlogic sells one as an accessory here: AutoVent Automatic Shelter Vent Kit
