Skip to main content

Reasons for cracks in plastering

Short answer

Plaster cracks are caused by shrinkage of rich mortar or poor curing, use of fine or clayey sand, and insufficient bond to a dry or smooth background. Structural movement, differential expansion at brick-concrete junctions without mesh, single-coat thick application, and rapid drying also lead to cracking.

What are the reasons behind development of cracks in plastering?

Cracks in plastering arise from:

  • Shrinkage of rich cement mortar (too much cement or water) or poor curing.
  • Poor quality sand (too fine or with clay and silt).
  • Poor bond to the background, dry or dusty wall, or smooth surface without a key.
  • Movement of the structure: settlement, thermal and moisture movement of the wall or frame.
  • Different materials meeting at one surface (brick and RCC) without mesh or a joint.
  • Excess thickness applied in a single coat.
  • Premature drying from sun and wind.
  • Vibration, overloading, or structural cracks passing through the plaster.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Building Technology chapter 9 questions →