When the roof was replaced, it was about 20-25 years old. Most of the sections of wood that were replaced (rotted through) were under a tree (which is no longer there). Yes there was some mold, and at the time, only blocked soffet vents and the one gable for venting.
The roofer didn't feel the ridge vent was needed, and opted to put in the 3 mushroom vents (roof is about 60' x 25' x 3' (highest at peak). each Mushroom vent is about 15 apart, with the center vent with a power fan (although the fan is thermostatically controlled, not moisture controlled). And he unblocked the soffets.
OK. now the hard quesition. Should the roofer pay to put the ridge vent in? I wasn't charged for a ridge vent, only the mushrooms. Actually the other estimates we had were for ridge vents. When the work started, we inquired about where the cuts for the ridge vent were going to be, and they held a little meeting, and came to the conclusion that we didn't need it, although they did say they would put one in if we wanted it (and would be extra above the estimate given, which did NOT say ridge vent).