Construction waste presents a significant problem for both the environment and public health. Divided into hazardous and recyclable categories, they require special treatment during disposal. Harmful materials such as asbestos or lead can pose serious threats to human health and the environment. Therefore, special caution and appropriate safety procedures should be followed during construction, use, or demolition of buildings containing these materials. The article discusses the impact of defects occurring in the joints of prefabricated buildings on the change in internal stresses and the deflection angle of the ceiling slab. Four models were used for analysis: a reference model, one considering reinforcement bar corrosion, one considering voids in the joint material, and one considering reduced material parameters. The results showed that models with defects exhibited higher stresses and deflection angles compared to the reference model. For example, the corrosion model showed an increase in tensile stresses in the reinforcement by 58%, and models with voids had tensile stresses in the reinforcement even 80.7% higher. The safety factor values for concrete also indicated hazardous areas where the material was already damaged. These results suggest the need to consider defects during structural diagnostics and decision-making regarding repairs or replacement of damaged elements. Materials such as concrete, plastics, or steel can be relatively easily recycled, contributing to waste reduction. Due to the dynamic development of material engineering, many products are available on the market for repairing damaged structural elements, eliminating the need for their replacement and reducing waste generation.