The building envelope consists of a roof, exterior walls (brick or glazing), and windows. The primary function of the building envelope is to keep the weather out. It prevents the entry of rainwater and excessive sunlight into the building. Besides, the building envelope also provides the necessary sound insulation for outdoor activity and traffic noise to the occupants. Thus, improper maintenance of the building envelope leads to cracks in floors, door systems that misaligned and drag, and water infiltration into lower levels.