We have owned 6 various kinds of RV's over 40 years; currently a 30 ft. Class C motorhome and have never had the luxury of storing them under a roof and the same goes for all of the cars and trucks I've owned. We live in west central Illinois. My cars always still shine when I sell them and I've never seen any damage that I could directly attribute to being exposed. Also, I'm lazy and covering isn't all good anyway. Difficult to keep the wind from blowing the cover around, etc. You do want to fix any water leaks coming from the roof because the rain and snow would add to such a problem but hasn't happened to me yet.