Ok sports fans, I have a problem.
Yesterday I walked around the deck and I see a puddle of water 2' in from the eve under the porch/roof transition line. Looking up there is a pretty steady drip and walking along the back porch(North side of house) I see 4 more smaller spots that are wet. I thought I had a leak, but no, it's apparently water vapor condensation on the underside of the metal roof. It was 28 degrees yesterday morning and there was a frost. At the time I walked around it was 11AM and the sun was full on the South side of the roof. There was no drip/leak on the South side porch which means it must have been burned off by the sun. Here are the pic's:
Puddle:
The exit point of the water:
Another spot about 8' in from the eve:
Remember...on the roof, I have 1.5" decking, then 30 weight tar paper, then 3" styrofoam, then purlins, then tin. On the porch I have 4/4 oak decking, then 2" high density foam with vapor barrier backing, then purlins, then tin.
Pondering this I think I should have also put tar paper under porch roof and tucked it up under the transition so any water would continue out over the porch and exit. But, my concern is that no matter what I do I will have this melting water vapor under the right weather conditions and it will still be running down between the tin and the purlins. Since the purlins all run horizontally water will collect/soak in/collect eventually causing an issue.
Maybe this is not a big deal, but it bothers me to have that much moisture between the foam insulation and the tin and I have to wonder if there is a definitive solution???