incorrect installation?

There are many different brands and types of metal roofs. Without knowing exactly what has been installed, I cannot say whether this was an appropriate installation. Generally, though, I do suggest plywood for residential applications. Having good attic ventilation as well as sealing against any leaks of heat from the living space to the roof assembly would help avoid ice dams which it sounds like is another issue you have had.

I bought a mobile home and changed the roof from a flat shingled roof to a pitched metal roof. The new roof was done in July 2013. January 1, 2014, my new roof started leaking, 30 water spots and counting. The gutters were nailed on and due to the snow build up on my roof, the gutters, fascia and soffit came crashing down yesterday. The metal roof was installed directly on the 2x6 frame of the roof. I have been told that there should be plywood and a rubber membrane under the metal roof. Also, the old shingled roof was never removed before the frame for the pitched metal roof was put on. The contractor explained that one of the benefits of a metal roof is that the snow and ice would not accumulate on the roof. I'm assuming that is not correct. My question... What is the proper installation of a pitched metal roof? Should there be plywood and some sort of weatherproofing? should the old roof have been removed or is that just a matter of preference?