How to Repair Drywall Cracks: A Step-by-Step Guide
Drywall cracks appear when house settling, temperature changes, or moisture cause the material to shift and separate. Most small to medium cracks can be fixed with spackling compound or joint compound for $10-30 in materials. This repair involves cleaning the crack, filling it with compound, sanding smooth, and painting—a task any homeowner can complete without special tools.
Step-by-Step Fix
- 1
Clean the crack
Use a putty knife to scrape away any loose drywall, dust, or debris from inside the crack. Make the edges as clean as possible so the filler compound adheres properly. Wipe the area with a damp cloth to remove remaining dust, then let it dry completely.
- 2
Apply joint compound or spackling
Fill small hairline cracks (under 1/4 inch) with lightweight spackling compound using a putty knife. For cracks wider than 1/4 inch, apply joint compound in two thin coats rather than one thick coat. Press firmly into the crack and smooth the surface level with the surrounding drywall.
- 3
Sand the dried compound smooth
After the compound dries completely (check the package for timing, usually 1-3 hours), sand the area with 120-150 grit sandpaper until flush with the wall. Use light pressure and a sanding block to avoid creating dips. Wipe away all dust with a damp cloth before the next step.
- 4
Apply a second coat if needed
For deeper or wider cracks, apply a thin second coat of compound to ensure a seamless finish. Sand again once dry. This extra step prevents the repair from shrinking and becoming visible after painting.
- 5
Prime and paint the repair
Apply primer to the filled area to seal it and ensure consistent paint coverage. Once dry, paint over the repair with your wall color using a small brush or foam applicator. Blend the edges into the surrounding wall for an invisible finish.
⚠️ Safety Notes
- Wear a dust mask when sanding dried compound to avoid inhaling fine particles.
- If cracks reappear within weeks or grow wider than 1/2 inch, the issue may be structural settling or moisture problems—call a pro to assess.
- Ensure the wall is completely dry before filling; moisture can prevent compound from bonding and cause future failure.
When to Call a Pro
Call a professional if cracks are wider than 1/2 inch, run diagonally across the wall in a stair-step pattern, or keep reappearing after repair—these signs indicate foundation movement or water damage that needs expert diagnosis.
Frequently Asked Questions
- What's the difference between spackling compound and joint compound?
- Spackling compound is thicker and designed for small cracks under 1/4 inch; it shrinks less and dries faster (30 minutes to 1 hour). Joint compound is thinner, better for larger cracks and wider repairs, and requires multiple coats but creates a smoother finish.
- How do I prevent drywall cracks from coming back?
- Most cracks return if the underlying cause—settling, humidity swings, or structural movement—isn't addressed. Minor cracks can be prevented by maintaining steady indoor humidity (30-50%), but recurring cracks signal a need for professional inspection.
- Can I paint directly over a drywall crack without filling it?
- No. Paint alone won't hide or repair a crack; it will crack again as the wall continues to move. You must fill the crack with compound, sand it smooth, and then prime and paint for a lasting repair.
- What grit sandpaper should I use for drywall compound?
- Use 120-150 grit sandpaper for the final finish; avoid coarser grits (80-100) as they leave visible scratches. For a final smoothing before paint, you can use 220 grit for a polished result.
- How long does a drywall crack repair last?
- A properly filled and painted crack should last indefinitely if the wall remains stable. However, if the crack was caused by settling or moisture, it may reappear within months to a year as the underlying issue continues.
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