I have a interior soffit (that encloses a structural beam running along the exterior of the building) directly above an exterior sliding door. The drywall covering this soffit abuts right up against the door's metal frame. From what I can see, the original drywall installers just ran the 5/8 in gypsum board right up to the metal frame and possibly used some mud to get a nice clean-looking line. Below is a detailed view of this area showing the bottom of soffit (top of image) against the metal door frame (left):
The metal door frame apparently does not have a thermal break and can therefore get very cold. It is also prone to interior condensation even when interior humidity is well controlled (as is visible in the image). My concern is that this condensation may also be occurring up inside the soffit and causing damage to the backside of the drywall. There are some signs of this happening already (bubbling tape seams near frame, etc.). Exterior water penetration has been ruled out.
My question is how is this intersection of dissimilar materials supposed to be finished given the characteristics of this metal frame? I'm assuming that at a minimum some sort of J bead should have been used around the edge of the drywall to create a buffer and make sure the paper backside of the drywall can't touch any sweating metal. If so, would it be possible to retrofit one? Also, even with a J Bead should some sort of air gap be left (maybe 1/8 in) next to the metal to allow for circulation and drainage, or would that just encourage more condensation? Of course an airtight seal is likely impossible no matter what.