How to Repair Cracked Plaster Walls

Fill small cracks with spackling compound or caulk, sand smooth when dry, and paint. Larger cracks need mesh tape and joint compound applied in thin layers.

1. Know Your Crack Type. Remove any loose plaster debris from the crack using a putty knife or brush. Wipe the area clean with a damp cloth. Examine the crack to determine if it's hairline (less than 1/8 inch), medium (1/8 to 1/4 inch), or large (over 1/4 inch). This determines your repair approach.
2. Seal the Smallest Gaps. For cracks smaller than 1/8 inch, simply clean them out and apply paintable acrylic caulk directly into the crack. Smooth with your finger and wipe excess immediately. Let dry completely before painting.
3. Fill Medium Fractures. For cracks between 1/8 and 1/4 inch, use spackling compound or lightweight joint compound. Apply with a putty knife, pressing firmly to fill the crack completely. Scrape excess flush with the wall surface. Allow to dry for 2-4 hours depending on thickness.
4. Tape and Layer Large Breaks. For cracks over 1/4 inch, apply mesh tape over the crack first. Spread a thin layer of joint compound over the tape with a 6-inch putty knife, feathering the edges. Let dry completely, then apply a second coat, extending it wider than the first. Sand lightly between coats if needed.
5. Sand Seamlessly Smooth. Once completely dry, sand the repaired area with 120-grit sandpaper until it's flush with the surrounding wall. Use circular motions and light pressure. Wipe away dust with a tack cloth or damp rag.
6. Vanish the Repair. Apply primer to the repaired area to ensure even paint absorption. Once primer is dry, paint the area to match the surrounding wall. You may need two coats for complete coverage and color matching.