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I need some help figuring out how to fix what I am thinking is a vent/condensation problem. I have a drywall, cathedral ceiling that butts up against a chimney. The chimney has the proper 2" of air gap between the chimney and final rafter. I think this is for fire protection? Anyway, I'm getting condensation right up against the chimney from the air gap area and it runs down my chimney at the same time every day when it's hot out (1PM I start to see dark spots on the brick inside).

I did experience a leak in this area about 3 years ago, but I had a roofer add a cricket, re-flash, new OSB and shingle the problem area. I'm mentioning this because it's very close to my problem area. Since the initial work, I've had zero issues until this summer. If you look at the attached PDF, I've even torn apart the roof since the repair to check for any problems w/flashing, etc.

Now, onto what I think is going on: I think I have a condensation/dew point problem due to the high temp, high humidity that we're experiencing in the Maryland area for the past 2 weeks. Typical temp around 1PM is around 90F, sometimes higher. The humidity has been hovering around 60% at this time. The moulding that is installed against the brick chimney/drywall is definitely NOT air tight and I think when the cooler air in the room escapes through the cracks it hits the hot air in this air gap space and causes condensation. Am I crazy?

What is the proper way to fix this issue? I'm already tearing out the molded drywall (see pics in the attached PDF) and using a dehumidifier to dry the area out and stop the moisture, but what is the proper, long-term fix for this? Soffit vents are present for this roof section, but no ridge vent or "escape" are present. The red line on the roof in the attached PDF is the peak of this troubled cathedral area.

Please let me know what other pics you guys need to help me out.

90F, 60% humidity = Dew Point of 74F
I keep my AC set to 71F :)

I bought an older home (built in 1975) and have been slowly upgrading and fixing issues that are common in older construction. This one has me baffled, no pun intended.
 

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