10-03-2015, 11:29 PM
Not just the steel I-beams, but the other challenge with flat roofs is drainage: snow melts and sits on the roof, eventually it will find some way through the roof, and presto, you have a leak into the house. Back in my homeland, lots of flat-roof houses were built in the 70s; by now, most of them have been converted to conventional roofs, due to the snow and leaking issues.