Cracks along drywall seams, in corners, and around windows and doors are common as houses settle and temperature changes cause expansion and contraction. These cracks look alarming but are usually cosmetic rather than structural. The fix is straightforward — retape the joint and finish it properly.

How to Fix Drywall Cracks

Why Drywall Cracks

Drywall cracks appear at joints where two sheets meet because that is the weakest point in the wall. The joint tape that bridges the seam can lose adhesion, and the joint compound beneath it can crack. Common causes include:

• Normal house settling over time
• Seasonal humidity and temperature changes
• Slamming doors creating vibration
• Poor original taping technique (insufficient compound under the tape)

If cracks reappear in the same location after repair, the movement may be ongoing. For cracks wider than 1/4 inch, diagonal cracks over doorways, or cracks accompanied by doors that no longer close properly, consult a structural professional.

Repairing Seam Cracks

Step 1: Remove the Failed Tape

Use a utility knife to cut along both sides of the damaged tape. Pull off the loose tape and scrape away any loose joint compound with a 6-inch drywall knife.

Step 2: Widen and Clean

Lightly scrape the area to remove any compound that is not firmly bonded. You want a clean, stable surface for the new tape to adhere to.

Step 3: Apply New Tape

Use fiberglass mesh tape for crack repairs rather than paper tape. Mesh tape is self-adhesive and more flexible, which resists cracking better. Press it firmly over the cleaned joint.

Step 4: Mud Over the Tape

Apply a thin coat of joint compound over the mesh tape with a 6-inch drywall knife, pressing compound into the mesh. Extend the compound 2 to 3 inches beyond the tape edges.

Step 5: Second and Third Coats

After each coat dries (overnight for standard compound, 45 minutes for quick-set), apply another thin coat with progressively wider knives — 8-inch, then 10 or 12-inch. Feather the edges into the surrounding wall so there is no visible ridge.

Step 6: Sand and Paint

Sand smooth with 150-grit then 220-grit sandpaper. Prime with a PVA primer before painting to prevent the repaired area from showing through.

Repairing Corner Cracks

Inside corners crack more often than flat seams because they absorb the most building movement.

1. Remove loose tape from the corner
2. Apply pre-formed paper corner tape or fold a strip of paper drywall tape along its center crease
3. Embed the tape in a thin layer of joint compound applied to both sides of the corner
4. Smooth with a corner trowel or by running a drywall knife along each side of the corner
5. Apply second and third coats, sanding between each
6. Prime and paint

Repairing Cracks Around Windows and Doors

Cracks at the corners of window and door openings are caused by stress concentration at those points. The framing flexes, and the joint at the corner of the opening cracks.

1. Cut out and remove the damaged tape and loose compound
2. Apply mesh tape over the crack, extending well past the crack endpoints
3. Apply multiple thin coats of compound, feathering outward
4. For recurring cracks, use flexible crack repair compound (like DAP ElastoPatch) instead of standard joint compound — it remains flexible and resists re-cracking

Using Quick-Set Compound

Quick-set (hot mud) joint compound sets by chemical reaction rather than drying, allowing you to apply multiple coats in a single day. Mix only what you can use in the working time indicated (20, 45, or 90 minutes). This is the most efficient approach for drywall repairs where you want to finish in one session.

Tools Needed

• 6-inch, 8-inch, and 12-inch drywall knives
• Utility knife
• Sanding sponge or sandpaper (150 and 220 grit)
• Mud pan
• Joint compound and fiberglass mesh tape
• Primer

Prevention

• Maintain consistent indoor humidity (30 to 50 percent) to minimize wood framing movement
• Use flexible caulk rather than rigid joint compound where walls meet ceilings if cracking recurs
• Install expansion joints in long drywall runs as recommended by drywall manufacturers

Seam and corner cracks are normal and repairable. With proper technique and flexible materials, repaired cracks stay invisible for years.