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Added Attic Framing Picture to provide more clarity per comments below

I am currently adding a picture window to an existing gable end wall. This gable end wall is part of a room with a cathedral/vaulted ceiling. I know how to frame it with king studs, a header, jacks, sill, cripples/etc. However, I'm not sure how to support the ceiling above since it's on a pitch while framing. Does the gable end NEED a temporary support wall and if so, how would you build one in this space?

Image is attached with red indicating where the new picture window will be located.  Existing window to the left will be framed in and closed up.

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  • It's an exterior wall, so it has (OSB?) sheathing, right?
    – Huesmann
    Commented Feb 2 at 15:11
  • No, it's fiberboard. I'm actually going to re-sheath the house in OSB as part of this project, but at the time of this framing it will still be the fiberboard so not a lot of structural strength to the sheathing.
    – Chris
    Commented Feb 2 at 15:19
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    Gable ends usually do not have much load on them, compared to the walls the joists/rafters sit on.
    – crip659
    Commented Feb 2 at 15:19
  • I've seen as much online, but wasn't sure if it being cathedral/vaulted put more load on the gable or not. Very little on the topic I can find.
    – Chris
    Commented Feb 2 at 15:22
  • I can't imagine the framing not being able to support the end rafter while you cut the hole. (Assuming the existing window has a proper header.) Do you know if the framing goes all the way to the top, or if the gable is framed separately from the wall?
    – Huesmann
    Commented Feb 2 at 15:24

2 Answers 2

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Assuming a modern engineered (scissor) truss system, you do not need to support the ceiling. You have common trusses running across the room to support the ceiling, and there's a gable truss over the wall which will carry the outer roof. You can cut your opening without concern of settling. The wall as a system, even with just fiber sheathing, will be stable.

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  • Could be ordinary rafters with a structural ridge beam. That ceiling slope looks 4:12. It's effectively a distinction without a difference, though.
    – popham
    Commented Feb 2 at 18:10
  • Yeah, but having seen a wide variety of creative roof framing strategies in my experience I have less confidence in those. If they're done to established standards, sure.
    – isherwood
    Commented Feb 2 at 19:01
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    I almost forgot about this guy's ceiling: diy.stackexchange.com/questions/284001/…. Your "creative" reminded me. If you read through that mess of comments, he had a header running parallel to the rake. Framing running perpendicular to the rake. I imagined "rafters" tipped over at 18 degrees at the time. Could have been purlins, I guess.
    – popham
    Commented Feb 2 at 19:16
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A year ago I would have said that the gable end is always non-load bearing, so don't worry about it. This guy, however, had a load bearing gable end with vaulted ceilings like yours. You should knock on the ceiling along the gable end and perpendicular to the gable end to verify that the rafters run parallel to the gable end. What you're looking for is rafters parallel to the gable end with a rafter located within 24" of the gable end. That implies that your wall is non-load bearing.

See IRC R602.7.4 for the header size in a non-load bearing wall. Just a flat 2x4.

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  • Or, just stick a head up into the attic space.
    – FreeMan
    Commented Feb 2 at 20:05
  • @FreeMan, yeah, I would prefer to actually set eyes on the framing. For scissor trusses that's possible (you can at least extrapolate that scissor trusses at your access location imply parallel scissor trusses all the way across). For vaulted ceilings plus rafters, though, there's probably no access. 4:12 is the minimum slope for asphalt shingles without special detailing (see IRC R905.2.2), so seeing a ceiling with about the 4:12 slope makes me think "rafters."
    – popham
    Commented Feb 2 at 20:16
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    I added an additional picture from the attic where I got a shot of the framing up there. The gable is at the far end of the picture.
    – Chris
    Commented Feb 2 at 22:08
  • @Chris, confirmed that's not load bearing. Like I said, isherwood's answer is correct 99.99% of the time. It doesn't hurt to check, though.
    – popham
    Commented Feb 2 at 22:13

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