Why These Cracks Keep Coming Back
The reason a recurring crack keeps recurring is almost always that the repair didn't address the movement. The crack isn't a cosmetic problem on its own. It's a symptom of the wall moving, either seasonally or because of something structural happening underneath.
In my case it was seasonal. Northwest Ohio gets cold winters and warm humid summers, and wood framing contracts in winter and expands in summer. That movement shows up most visibly at stress points: corners, window openings, door frames. The diagonal from a window corner is classic wood movement crack behavior, and it's been doing this in my house since at least 2012 based on the old paint layers I saw when I finally opened it up properly.
Filling it with a rigid compound and painting over it just gives the movement something new to crack through. The next cycle of expansion and contraction breaks the repair exactly like it broke the original surface. You're not fixing anything. You're resetting the clock.
What I'd Been Doing Wrong
Lightweight all-purpose compound. That's what I'd been using both times, and it's what most people reach for because it's what's sitting on the shelf at every hardware store. It's fine for finishing seams and filling nail holes. It's not designed to flex with movement.
I'd also been filling the crack without widening it first. Just pressing compound into the existing crack line and smoothing it flat. Which meant I had maybe a millimeter of compound sitting in a narrow gap with no real mechanical bond to either side.
The third time I sat there looking at it, I actually went and read some manufacturer documentation before doing anything. USG's guidance on crack repair specifically addresses this: cracks caused by settlement or ongoing movement need a flexible treatment, not a rigid fill. I had been solving the wrong problem. Twice.
The Repair That Actually Held
I opened the crack up first. Used a utility knife to cut a V-groove along the crack line, about a quarter inch wide and an eighth inch deep. This sounds counterintuitive when you're trying to make a wall smooth, but it gives the repair material something to grip and allows it to flex slightly without telegraphing through the surface.
Then I used paintable caulk instead of compound. Specifically, a siliconized acrylic caulk rated for interior use. Pressed it into the groove, smoothed it with a damp finger, let it cure for 24 hours. After the caulk was fully cured, I skim-coated over it with a thin layer of all-purpose compound, just enough to blend the repair into the surrounding wall surface and give me something I could sand smooth.
That was in the fall of 2022. The repair is still intact. It went through two Ohio winters and two summers without cracking again. Pete tried the same approach on his house and had the same result, though he called me about four times during the process asking questions I mostly answered correctly.
What I Spent
DAP Alex Plus Paintable Caulk, the clear-drying formula. Cost me $5.87 at Home Depot. A small tub of lightweight all-purpose compound for the skim coat. Total materials were under $15, which was less than I'd spent on either of the two previous repairs that didn't work. That part was genuinely annoying to think about.
Caulk vs. Compound: When to Use Which
The rule I follow now: if the crack is at a location where two different materials meet, or where wood framing creates a stress point, caulk first. This includes corners where walls meet ceilings, the perimeter of window and door frames, and diagonal cracks running from those corners.
Compound-only repairs work fine for cracks in the middle of a wall where there's no directional stress, for lifting tape, for nail pops, and for holes. Basically anywhere the problem isn't ongoing movement.
You can put compound over cured caulk, which makes it easier to blend the repair and sand it smooth. You cannot reliably put caulk over compound because caulk won't bond properly to a dusty or porous compound surface. Order matters.
When to Worry About Structural Movement
Window corner cracks and diagonal stress cracks in residential drywall are usually cosmetic, caused by normal seasonal wood movement. The repair I've described is appropriate for those.
If you have a crack that's actively growing over weeks or months, that's wider than a quarter inch, that appeared suddenly after a specific event (heavy rain, nearby foundation work, a hard freeze followed by a fast thaw), or that comes with doors and windows sticking differently than they used to, that's a different situation. The University of Illinois Extension has a straightforward reference on distinguishing cosmetic settling cracks from structural movement in older homes, and it's worth reading if any of those symptoms apply to your house.
My crack was a cosmetic seasonal crack. I was just fixing it wrong. That's probably true for most people reading this. But it's worth knowing where the line is, because the repair for structural movement is not a caulk job and a skim coat.