The roof construction is wood I beam 16" high, then 3/4" plywood with black paper with metal roof on top of that. The underside has R19 faced insulation with T&G ceiling. This system leaks from condensation on the north faceing part of the roof. I have made sure the soffit area is clear from insulation, but I can not see if there is a space between the insulation and roof plywood all the way up to the ridge. The leaks happen half way down the span of the ceiling to the outaide wall. Any suggestions?