Hi, I need some help with this one:
I’ve got a post and beam ranch style home with vaulted ceilings. There are three main beams (one ridge, two mid on either side) running the length of the house with rafters on top. From inside out the roof over the vaulted area is drywall (nailed to the bottom of th rafters and between the beams), plastic vapor barrier, styrofoam block insulation, 1 3/4" air gap, 3/4" plywood deck, paper & shield and shingles. There is finish trim nailed at all points where the drywall meets the beams. The plastic vapor barrier stops right at each beam as well so it makes a good place for condensation to exit the roof system without ruining the drywall. There is a continuous soffit vent and continuous ridge vent except for 32" where their is adjacent skylights on either side of the ridge above the chimney. The chimney is midway up the roof. Had a new roof (tamko asphalt shingles) put on in August.
Started having drips the length of the mid beam on the side of the house with the vaulted ceiling when it snows but nothing from rain, not even during torrential downpour. The roofer claims that it is condensation and not his problem, which does make sense (the condensation). The air is 65 deg. F, the humidity is 33%, so the dewpoint should be approximately 35 deg. F.
I used a thermal scanner with picture overlay on the roof. There are hot spots around the chimney flashing, skylights, and the gap between two sets of rafters appear to be 7 degrees hotter than the rest. I measured the rafters and checked below. There is recessed lighting in those two sets of rafters. I pulled the cans and they are not sealed. There was one or two nails with condensation behind each can but it was by no means wet in those rafters while at the same time I had drips coming down along the mid beam just below the lights and a few feet away laterally. The thermal image shows the heat starting at the lowest light and exiting the ridge as it should so I’m guessing the airflow is adequate in at least those two rafters to not be the source.
The roof overhangs on each end. On one of the overhangs there is also water running down the soffit (not sure if its called soffit on the overhang at the end but don’t have a better term for it) just below the ridge beam. It seems odd to have leaks there because there is at least one joist between the leak and the exterior wall of the house. It is almost like the ridge is not allowing the air out at that joist.
I’m at a loss as to what could be the source of the condensation on the midbeam other than maybe the chimney since the laminated beam that is dripping runs through the edge of the chimney. Without tearing out a lot of ceiling drywall I’m not sure if they put any type of cross ventillation on the rafters below and between the chimney and skylight as those would be dead air spaces. Additionally, the drips are coming down 25’ in either direction of the chimney and based on my 4’ level at the ends the water would have to defy gravity for the chimney to be the source.
I’ve called some other roofers and contractors to come give second opinions but was wondering if any of you have come across something like this before? If so I’m open to any ideas to remedy the situation.