Deterioration refers to the gradual decline in the quality, strength, durability and serviceability of a building material or structure due to the combined effects of environmental exposure, load conditions, chemical reactions, poor workmanship, aging, and lack of maintenance. In the context of building services and maintenance, deterioration is a critical concern because it directly affects structural safety, functionality of services, aesthetic appearance, and overall life cycle cost of a building. It may occur in concrete, masonry, steel, timber, plaster, and finishing materials, and is often progressive in nature if not identified and treated at an early stage. Deterioration can be classified broadly into physical, chemical, mechanical and biological forms. Physical deterioration occurs due to temperature variations, freeze-thaw cycles, moisture movement, and abrasion. Chemical deterioration results from reactions such as carbonation, sulphate attack, chloride ingress, and corrosion of reinforcement. Mechanical deterioration is caused by overloading, vibration, impact or settlement, while biological deterioration may result from fungi, termites, algae, and other organisms. In reinforced concrete structures especially, deterioration commonly manifests in the form of cracking, scaling, spalling and delamination, each of which indicates varying degrees of damage and underlying structural distress. Cracking is one of the earliest and most common signs of deterioration in buildings. A crack is defined as a visible linear fracture or separation in a material such as concrete, plaster, or masonry. Cracks may vary in width, depth, direction and pattern depending on the cause. They can be classified as structural or non-structural. Structural cracks occur due to excessive loading, foundation settlement, design deficiencies, or seismic activity, and may compromise the load-carrying capacity of the structure. Non-structural cracks are generally caused by shrinkage, temperature variation, creep, or minor movement and may not immediately affect structural stability but can lead to moisture ingress and further deterioration. In concrete structures, cracking may occur due to plastic shrinkage during early stages of curing, drying shrinkage over time, thermal expansion and contraction, or corrosion of embedded steel reinforcement. When reinforcement corrodes, it expands in volume, exerting internal pressure that results in cracking along the reinforcement lines. Cracks also develop due to differential settlement of foundations, improper construction joints, and inadequate curing practices. Although some minor hairline cracks are unavoidable and may not be harmful, wider cracks can permit the entry of water, carbon dioxide, chlorides and other aggressive agents, accelerating corrosion and structural degradation. Regular inspection, crack monitoring, and appropriate repair techniques such as grouting,