Condensation in attic with a steel roof

In 2005, I added an addition to my home and had a new asphalt roof installed. I had no problems before that time or since....until, in 2007 thanks to a hail storm, my asphalt roof was damaged. A friend recommended steel, and since he was a contractor, he could install it for a reasonable deal. That was September 2007. Christmas day, 2007, during dinner, there was water dripping from the light fixture. I went into the attic, and the entire space was wet. The trusses and the plywood were saturated. I called my contractor and he came and looked at it and told me that I did not have enough insulation. So, we blew in 20 bags more of insulation. The problem did not go away. I had a building inspector look at it, and he said there was not enough ventilation. So, the contractor came and put in gable vents. Needless to say, I have the same wet issue, I now have mold growing down the walls on the inside of my exterior walls. Today, I went into the attic again, and there is so much water on the trusses and plywood. My wife and I want to sell our house because we are moving soon. What options do I have? Do I need to remove the steel and put asphalt shingles back? Thanks

Insulation has very little to do, or slows the movement of humidity into the attic space. In my opinion, the idea of attic ventilation is completely overused. It was designed originally to exhaust excess humidity that had migrated into the attic space and to prevent just that sort of condensation issue that you are having. You need to air seal the attic floor and stop the movement of condensation into the attic space. The reason that the attic is probably showing this condition now is because the attic temps are lower with the steel roof as compared to when the asphalt roof was in place. That drop in temp has allowed that moisture to condense in the attic and create that bulk moisture issue. This is all assuming, of course, that you don't have some sort of leak.