How to Fix a Crack in Stucco Block Walls

Stucco is a mortar-like mixture that builders apply over block wall surfaces to improve the appearance. Once dry, the stucco is hard and fairly durable. However, because stucco layers are thin, the stucco cracks if the ground shifts or if an object, such as a tree limb, hits it. Most stucco cracks are cosmetic, but they will lengthen if not repaired. Repairing the cracks requires that you fill them in with a mixture that closely resembles stucco once dry.

Screwdriver
Toothbrush
Exterior grade latex caulk
Paper cup
Sand
Popsicle stick
Plastic putty knife
Rag
Exterior-grade paint
Artist’s brush

Instructions

- 1
  Insert the blade of a slotted screwdriver into the crack and run it along the entire length to scrape out any loose debris inside of it, which may interfere with the stucco repair. Brush the exterior surface of the crack with a toothbrush to remove any dust or chips from the surface of the crack.
- 2
  Open a tube of exterior-grade latex caulk and squeeze 1 to 2 tablespoons into a paper cup. Add 1 to 2 teaspoons of sand to the cup and stir it in well using a Popsicle stick. Choose sand that is the same color as the stucco wall that you are repairing.
- 3
  Scoop up 1 or 2 teaspoons of the caulk mixture using a plastic putty knife. Start at the top of the crack and press the caulk mixture into it until it fills to the top. Continue pressing the caulk into the crack until you reach the bottom end of the crack.
- 4
  Dampen a rag with water and wipe the entire surface of the stucco wall around the crack to remove the excess caulk mixture.
- 5
  Wait until the caulk mixture dries completely. Apply an exterior-grade latex paint to the crack in the same color as the surrounding stucco. Use an artist’s brush to apply the paint only to the caulked area.

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