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Causes of cracks in a building

Short answer

Main causes: moisture movement (shrinkage/expansion), thermal expansion, differential foundation settlement, elastic deformation from overload, reinforcement corrosion, chemical attack (sulphate, alkali-aggregate), vegetation roots, earthquake, wind, poor workmanship, overloading, design errors, fire.

What are the main causes of cracks in a building?

A crack is a visible separation in a wall, slab, plaster or any other building element. Cracks can be structural or non-structural. The main causes are as follows.

CauseHow it cracks the building
Moisture movementBricks, blocks and concrete expand on wetting and shrink on drying; mortar and plaster shrinkage
Thermal movementExpansion and contraction with temperature in roofs, long walls, parapets
Settlement of foundationUnequal settlement due to poor or non-uniform soil, wrong foundation level, change in moisture, or inadequate depth
Elastic deformationOverload, deflection of beams and slabs, bending and shear
Corrosion of reinforcementRust expands and splits the concrete cover
Chemical actionSulphate attack, alkali-aggregate reaction, carbonation
VegetationRoots of trees near walls and foundations
Earthquake and windLateral forces on weak walls and joints
Poor workmanship and materialsPoor curing, mix, bonding, early removal of formwork, missing joints
Overloading and design errorExcess load, wrong detailing
Fire, vibrationHeat damage, machine vibration

Prevention

  • Investigate the soil properly and design the foundation for uniform settlement.
  • Provide expansion, contraction and construction joints.
  • Use good materials and a proper mortar mix; cure for at least 7 days.
  • Provide plinth, lintel and roof bands.
  • Protect reinforcement with enough cover.
  • Remove vegetation near the foundation.
  • Waterproof the roof and walls.

✓ Answer checked by Claude Opus 5.5 (high effort)

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