How can I tell if corner bead is loose?

A hollow tap, a ridge that moves when pressed, or a crack that follows the bead edge points toward a local attachment or compound problem.

Should I sand a drywall corner crack flat?

Only after confirming the bead and substrate are stable. Sanding cannot fix movement, dampness, or a detached bead.

When is a corner crack more than a cosmetic repair?

When it widens, returns, follows a larger wall crack, has moisture evidence, or is accompanied by movement or distortion.

Drywall Corner-Bead Cracks: What the Pattern Tells You

A crack on a drywall outside corner can come from a loose bead, impact, poor compound coverage, moisture, or movement. The pattern decides whether a cosmetic repair is sensible.

Start with the crack’s position

If the crack tracks one edge of the outside corner, the bead or its compound may be the local failure. If it crosses the corner, opens and closes with movement, or continues across the wall, treat it as a wider movement question. Brown staining, soft board, or a musty smell moves moisture to the front of the queue.

A simple decision tree

Photograph the corner in side light and mark the ends of the crack.
Press gently beside the crack. Stop if the board flexes, crumbles, or feels damp.
Tap the area and compare it with a sound section of the same corner.
Check whether doors, trim, or nearby joints show new movement.
Repair only when the bead and wall are dry, firm, and stable.

For a stable local failure, remove loose compound, secure or replace the damaged bead only as the system instructions allow, then rebuild thin coats and feather the edges. Do not create a hard hump by filling the whole corner in one pass.

When to stop

Stop cosmetic work if the crack returns, the wall is damp, the corner is distorted, the damage follows a ceiling or opening, or you suspect structural movement. A corner can be the visible end of a problem that needs inspection elsewhere.

Limits

No corner was inspected and no universal repair material or drying schedule is prescribed. Product instructions, moisture control, and qualified local advice control the actual repair.

Start with the crack’s position

A simple decision tree

When to stop

Limits

Sources and related reading

See Also