I am renovating my son's bedroom and trying to make the walls as nice as is reasonable before repainting. There are a few cracks like this in the paint. It looks like on top of the drywall there is paint, wallpaper, and then a few more layers of paint. The cracks could be at the seams of the drywall from expansion and contraction. They could be at the seams of the wallpaper. They could be something else. Most of the cracks come straightish down below the sides of windows, which makes me think drywall seams.
I gouged out one crack and filled it with joint compound to see how that works. Since the drywall is old, it was really hard to tell if this is at a drywall seam or not - there are places where previous work, maybe mouse damage, and who knows what else has made the drywall crumble from behind. These are the joys of an older house!
How would you handle this?
You might want to use mesh tape on the big cracks to help stop recracking. I would poke around and see if the whole section is damaged too. You can replace large chuncks of drywall pretty easily and cheaply so no sense keeping damaged drywall if you're doing work anyway.
The biggest issue is what caused the crack to begin with. If it is settling, make sure there won't be any more of that before doing a repair to the crack.
Credentials - working on a house with foundation problems and water damage
Can I do mesh tape over the cracks as they are (with some initial sanding to remove high points), or do I need to strip it down to drywall first? Getting down to drywall would be tricky without damaging the drywall
Any settling should be long finished. The bedroom is on the second floor, and the additions that border these walls were completed ~30 years ago. The drywall in this room predates that addition, but these cracks are through layers of paint that came after the additions. Upon further inspection, I think the weak drywall is limited to a much smaller area than I first anticipated. That area has no cracks and will be trimmed with a cover out in for better plumbing access anyway.
It is your choice on sanding. Sanding down the crack/tape area below grade will make the flattest patch. The alternative is feathering out your joint compound further to hide the bump. You'll be surprised how thick tape seems when you're going for a smooth finish.
I like the flat (presanded) option because the bump option bothers me even though nobody else sees the difference.