Our kitchen/first floor was renovated about ten years ago. This included removing the 7 foot drop ceiling in the kitchen for a vaulted ceiling. So now the entire west side of the house from the kitchen through the family room is vaulted.
Over time, the ceiling has developed a crack at the transition from the old drywall to the new drywall. The crack runs from the outside wall (8 foot high) to the ridge beam (16 foot).
I could probably throw some caulk in the crack and paint match, but I suspect it won't last very long, plus near the top of the ceiling, the drywall tape is actually cracking and looks like parts of it wants to fall off.
My idea is to get some 1x3s or 1x4s, and put a faux beam along that seam. Then if it looks okay, maybe run one or two more, evenly spaced between it and the rest of the family room.
Could be from a myriad of reasons generally has to do with settling around here, usually pops up at 10-15 years and is associated with nail pops. Could also be from differential heating depending on roof and upstairs depending on the layout. 95% chance its nothing but cosmetic and faux beams would cover them hide the cracks. You could also use paintable silicone, it doesn't dry out like regular caulk and generally stays more flexible for longer.
Here is one I haven't gotten around to fixing in my house where the addition ties into the original house.
The crack follows the joint between old and new drywall - see pics below?
Found some pics from the remodel. Here is the kitchen area mid-tear down and after to show what was removed.
I'm thinking bad tape/joint work coupled with a little bit of settling over the years. I may try the paintable silicone first (assuming I can figure out how to color match the paint - time to check the garage and see if I still have anything left over).
Oh, and just because, here are a couple of after shots.
