Why These Cracks Keep Coming Back
The short answer: window frames move. Wood expands and contracts with humidity and temperature changes. Metal frames expand and contract with temperature too, but at different rates than drywall and framing lumber. Every season, the frame shifts slightly, and that shift is transmitted to the drywall at the corner.
When you fill a crack with rigid joint compound and it cures hard, you've created a rigid patch in a spot that's going to keep moving. The compound can't flex, so it cracks again, usually right along the original line or just beside it.
This is why mesh tape or paper tape over standard compound eventually fails here. You need something with flexibility in it, or you need to decouple the drywall edge from the frame entirely.
The Repair That Actually Stuck
The approach that finally worked for my living room crack was replacing the joint compound in the immediate corner with paintable caulk. Not compound, not mesh tape over compound — caulk.
The full process:
First, I removed everything that wasn't stuck solid. That meant pulling out all the old compound patches, going back to bare drywall surface. A stiff putty knife and some patience. Any loose paper facing came off too.
Then I feathered the area several inches back from the corner with a thin coat of compound, let it dry, sanded it smooth. The goal was making the surrounding drywall surface level so the final result blends in. This part is still standard joint compound work.
At the corner itself — the last quarter inch where drywall meets window frame — I ran a thin bead of paintable latex caulk. Smoothed it with a wet finger. That's it. No tape, no mesh, no compound on the joint itself.
The caulk can flex when the frame moves. The compound behind it is rigid but far enough from the joint that frame movement doesn't crack it. After two full winter-summer cycles, still holding.
Diagonal Corner Cracks vs. Edge Cracks
There are two different crack patterns I've seen at windows and they need slightly different approaches.
The first type runs at roughly 45 degrees from the window corner outward into the wall. These are almost always stress cracks caused by the window frame loading the drywall at a concentrated point. The FEMA guide on residential structural issues notes that diagonal cracking from openings is one of the most common stress indicators in residential walls, even when there's nothing structurally wrong — it's just the normal concentration of force at corners.
For these, the repair is removing the damaged section, cutting back to clean drywall, and doing a proper patch with paper tape. The diagonal crack isn't at the joint between drywall and frame, so caulk isn't the answer here. The key is cutting a clean edge for the patch and not trying to feather compound over the existing crack.
The second type runs along the seam where the drywall edge meets the window frame or window casing. That's the one caulk handles well.
When Settlement Is Involved
My house was built in 1978 and had some foundation settling that completed itself years before I bought it. Sandra's house was different — her cracks were more severe, and she'd had a couple new ones open up in the same year. When the crack pattern is actively changing, that's a different conversation.
If you've got window cracks that are widening year over year, or new cracks showing up across multiple windows in the same wall, it's worth getting someone in to look at the foundation and framing before you spend time on cosmetic repairs. The American Society of Home Inspectors recommends documentation — photographing cracks with a ruler for scale so you can track whether they're growing.
Active settlement changes the repair approach significantly. No point caulking a crack that's going to open again in six months because the foundation is still moving.
Painting Over the Repair
One thing that tripped me up early: caulk and compound take paint differently. If you paint over a repair that's half compound and half caulk without priming both, you'll see the line. The compound soaks up the first coat; the caulk sits on top.
Prime everything before painting, including the caulked joint. I use a shellac-based primer (Zinsser BIN) on repairs that involved any texture damage or bare paper exposure, and a standard drywall primer for everything else. Apply the primer, let it dry fully, then paint. The boundary between compound and caulk disappears.