In Egypt, construction projects produce a large amount of waste that reaches 40-50 million tons per year. Most construction wastes are landfilled or illegally dumped, causing land and water contamination. Construction waste can greatly affect construction project performance, as it affects the construction costs, time, productivity, and sustainability. In this research, the key influencing factors for waste management were investigated using a survey of construction practitioners in Egypt, so the waste can be controlled and reduced effectively. The study concluded that selecting contractors with the best experience in construction works and the usage of proper materials for storage facilities can significantly reduce waste generation. In addition, the proper planning layout of construction projects, using materials before expiry dates, and early communication on design changes between all contract parties are the key factors for waste minimization. A decision support system model, built on the relative importance from the analysis, is designed to support construction teams to improve the performance of construction and demolition waste reduction in construction sites.