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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):

enter image description here

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.

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  • soffit the ceiling of an exterior roof overhang - I am confused with your usage. Jan 19 '20 at 18:25
  • is that a single pane sliding glass door? it is one thing for the metal to sweat but if the glass is also sweating on the inside like that your humidity is too high. What is your rh? Jan 19 '20 at 18:26
  • @FreshCodemonger it's an interior soffit that's just an enclosure for structural elements, but it's along an exterior wall. I updated the question to clarify that.
    – rjacobs
    Jan 19 '20 at 18:51
  • Slider is double-pane but not very high-quality. As I noted the metal framing around it has no thermal break, which is in itself a significant insulation problem. RH is 35% or lower in winter but picture was taken during an especially big temp drop (single digits exterior temp). Condensation issues on metal frame is always much more significant than on windows, which is why I'm trying to unpack that factor.
    – rjacobs
    Jan 19 '20 at 18:56
  • I am leaving as a comment it might not be the best path forward but has worked on my Small house and a large animal doctors office. Hit return then took two long to edit, trying again I find using hot mud (fast drying) is the way to go, I started using hot mud with water resistant Sheetrock and fiberglass mesh to tape. The hot mud tolerates moisture it is like plastic where regular mud is like chalk. I have done rooms that were washed down with a hose regularly that held up quite well, If wicking use a strip of water resistant then hot mud, this worked for me on a low end place same type door
    – Ed Beal
    Jan 20 '20 at 18:11
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Searched for interior soffits seems some people use it instead of bulkheads. From the picture it just looks like you have a door with a header in an exterior wall.

When you say interior soffit this just means that a portion of the header is air space? As the thickness of the header is less than the thickness of the door? Typically you'd insulate the extra space using XPS. The backside of the drywall that covers the wall above the door looks flush with the interior surface of the door. Normally you'd use trim instead and have the surface of the drywall flush with the surface of the door frame but using drywall is sometimes done. In your picture it just looks like they've used the factor edge of the drywall - if that isn't already a j-bead. I don't think there is much you can do to provide more of a thermal break on the metal frame of that door.

In terms of moisture getting into the wall above the door, in a cold climate, there should be a vapor barrier (typically 6mil poly) that is on the warm side behind the drywall. This prevents water vapor from getting into wall spaces and condensing. Older homes (1920s) used vapor barrier paint.

Since it sounds like you have signs of moisture accumulating in the header space, I'd open it and make sure the vapor barrier is properly sealed with tape or acoustic caulking. For the intersection between the drywall and the metal door frame I'd be tempted to put sill gasket and then tape poly to the door frame and then put the drywall on top of that and use a slightly wider j-bead to return to the frame and then caulk the jbead to the frame. If you are already opening up the area around the door it wouldn't hurt to properly air seal the gap. I used backrod and energy seal and then a passive house tape like tescon vana to bridge between the metal frame of the door and the rough opening wood framing.

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    The moisture is from condensation metal framed doors like this (inexpensive) with no thermal break will sweat. Nothing will stop that, the op is asking how to minimize the problems.
    – Ed Beal
    Jan 20 '20 at 17:55
  • Although I do agree with air sealing.
    – Ed Beal
    Jan 20 '20 at 18:17
  • It's a multi-unit dwelling that's not wood-frame construction, so the "soffit" encloses a structural beam and a masonry element that sits above the sliding door. The beam itself is not directly above the door (like a normal header would be) and instead sits on the interior area of the room, hence the need for a soffit/enclosure. I've cut-away a section and you are exactly right regarding the "factor edge" (I assume the means "finished edge") of the drywall abutting the metal frame. This also means there's a lot of paper in contact with the metal.
    – rjacobs
    Jan 26 '20 at 1:10
  • Though the enclosure is insulated (standard batt insulation) I see no signs of a vapor barrier up there. The gap around the door frame itself also does not appear to be sealed on the interior side (just backer-rod and caulk on exterior side). These are all details that I'm going to have to look into. It looks like adding a J Bead will go a long way toward isolating moisture-sensitive elements from condensation-prone materials, but some special work will be needed to manage any moisture that may originate within the enclosure.
    – rjacobs
    Jan 26 '20 at 1:29
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The correct way to butt your drywall into this (problematic) metal frame is pretty much what you described.

Stop the drywall short about 1/4".

Add an L-Bead, or J-Bead, leaving the ~1/4"+/- gap. (An L-bead is much easier to put on after-the-fact.)

Use sealant with a backer rod to bridge between the two. (Wait for dry conditions to install the sealant for good adhesion)

Here is an image that pretty much shows this, though this particular company's bead (Trim-tex) has a bulb-seal on the L-Bead, which works too (that tab sticking up tears off after finishing). Though I'd still want sealant to make the gap blend in better.

Ignore the metal stud in that picture because it would also pose a condensation issue as it touches the cold metal frame.

L-Bead to frame

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