Overview

This repair targets cracks along drywall seams and damage to corner bead - the metal or vinyl strip that protects and shapes an outside (protruding) wall corner. These corners take a beating from vacuums, furniture, and foot traffic, and hairline cracking is one of the most common cosmetic drywall complaints. It's a reasonable project for a DIYer who's comfortable with basic tools, though getting a truly invisible corner takes a bit more finesse than a flat patch.

Tools & materials

  • Utility knife
  • Hacksaw or small oscillating multi-tool (only needed if replacing a section of bead)
  • Tape measure and pencil
  • Metal snips (if cutting new corner bead to length)
  • Replacement corner bead, metal or vinyl, matching the existing profile
  • Nails, drywall screws, or a stapler rated for corner bead, plus a hammer or drill
  • Paper drywall tape (for cracks not involving bead replacement)
  • Joint compound and a mud pan
  • 6-inch and 10-12 inch taping knives, plus a corner trowel if you have one
  • Fine-grit sandpaper or sanding sponge
  • Primer and matching paint
  • Dust mask and safety glasses

Steps

  1. Assess the damage: a simple hairline crack along the joint compound over intact bead is treated differently than a bent, dented, or rusted section of bead that needs to be cut out and replaced.
  2. For a hairline crack with the bead still straight and solid: use a utility knife to widen and clean out the crack slightly, removing any loose or crumbling compound.
  3. Apply a thin layer of joint compound over the cracked area, embed a strip of paper drywall tape into it, and smooth out excess compound and trapped air with a taping knife, feathering the edges a couple inches out on each side.
  4. For damaged or bent corner bead: mark a few inches above and below the damaged section, then cut it out with a hacksaw or oscillating tool.
  5. Score along the edges of the remaining bead with a utility knife and pry away the damaged piece by hand.
  6. Cut a new piece of matching corner bead to length and fasten it in place with nails, screws, or staples, checking with a level that the corner stays straight and plumb.
  7. Apply a first coat of joint compound over the new bead (or over the taped crack), feathering it out evenly on both sides of the corner. Let it dry fully - overnight is typical.
  8. Sand lightly, then apply a second, wider finishing coat, feathering it further out to blend the repair into the surrounding wall.
  9. Once fully dry, sand smooth with fine-grit sandpaper, wipe away dust, and check the corner from an angle in raking light for any ridges or low spots before priming.
  10. Prime the repaired area and paint to match the rest of the wall.

Safety warnings

  • Wear a dust mask or N95 respirator when sanding dried joint compound.
  • Wear safety glasses when cutting bead or sanding, especially overhead.
  • Wear work gloves when handling cut metal corner bead, which can have sharp edges.
  • Keep fingers clear of the blade path when scoring or cutting with a utility knife, and cut away from your body.
  • Use an oscillating tool or hacksaw carefully and unplug/power it down before changing blades.
  • Ventilate the room while sanding and painting, and lay down a drop cloth to contain dust and debris.
  • If the home was built before 1978, treat the old wall paint you're feathering into as a possible lead source - test it before dry-sanding, or dampen it and wipe instead, per EPA RRP guidance.
  • In pre-1980s homes, the existing joint compound at the seam can occasionally contain asbestos - test before dry-sanding a crack repair rather than assuming it's newer, asbestos-free compound.

When to call a pro

  • The crack keeps reopening in the same spot after two or more repair attempts, which often points to a structural or framing movement issue rather than a surface crack.
  • The crack is wide (more than about 1/4 inch), diagonal, or stair-stepped rather than a clean hairline along the seam.
  • You notice the crack paired with doors or windows that have started sticking, uneven floors, or gaps at the ceiling - signs of possible foundation settling.
  • There's water staining, bubbling paint, or a musty smell near the corner, suggesting a leak is contributing to the damage.
  • The corner bead is bent badly out of alignment across a long run (multiple sections), which is harder to get straight and plumb without experience.
  • The crack is on a high or hard-to-reach ceiling corner where safe access requires scaffolding rather than a stepladder.
  • You test (or suspect) asbestos in the old joint compound - stop sanding and call a certified abatement professional.

Cost estimate

About $15-$40 in materials for a DIY tape-and-crack repair or short bead replacement; professional corner bead repair typically runs about $100-$250+ depending on length and access.

Sources