Retrofitting adds new features or technology to existing structures to improve performance, safety, and compliance with current standards. This process is essential for extending the lifespan of buildings while enhancing their functionality and resilience.

The modulus of elasticity, or Young's modulus, measures a material's stiffness and resistance to deformation under load. It is the ratio of stress (force per unit area) to strain (proportional deformation) in the elastic range. This property is critical for designing structural elements to ensure they can withstand applied forces without excessive deformation.

The main types of construction materials include concrete (for foundations, slabs, and structural elements), steel (for frameworks and reinforcement), wood (for framing and finishes), masonry (brick and stone for walls), glass (for facades and windows), and composites (for specialized applications). Each material has unique properties and applications in construction.

Types of scaffolding include tube and clamp (versatile, assembled from individual tubes and connectors), system scaffolding (modular, quick assembly), suspended scaffolding (hung from above, for high-rise work), cantilever scaffolding (projects outward from structure), and rolling scaffolding (mobile, with lockable wheels). Each type has specific applications based on construction needs.

The bearing capacity of soil is the maximum load per unit area that the soil can support without failure. It is crucial for designing foundations to ensure stability and prevent excessive settlement. Factors affecting bearing capacity include soil type, density, moisture content, and depth of foundation.