Well, I wouldn't make that assumption. Besides, say you do add on and all is peachy. Won't the weight of the snow still be a factor, in addition to a whole second floor? I bet this turns into one of those things that is cost-prohibitive. Nothing money can't fix!!ya i will bring in an engineer, but wouldnt it be safe to assume that it could support a second floor since a flat roof in cleveland, ohio can get as much as 3' of snow sitting on it at any one time.