The environment is threatened severely by so many problems, some of which are caused by the activities of Construction Projects and its developments. The global concern to address environmental degradation caused by various developmental actions (construction projects inclusive) is the basis for calls to assess environmental impacts of building construction developments in worldwide. Data for the study were collated through a survey administered to stakeholders of building construction industries. Data collected were analyzed and ranked using Relative Importance Index (RII), result shows impacts listed are above the mid (RII) index of 3.0 suggesting that they significantly impact on the environment thereby causing environmental degradation. The research also reveals major environmental impacts of building construction projects to include environmental pollution, resource depletion and habitat destruction causing Destruction of ecosystem, Desertification, Soil Erosion and increasing Material Wastage.