Any building is basically an enclosure within which the environment is controlled.
The envelope between the enclosed space and the exterior environment plays a critical role in economically maintaining the desired internal environment. The major problems witnessed with brick veneer systems relate to the presence of moisture within the wall cavity. This moisture is forced into the cavities by rain penetration or by the movement of humid interior air from inside the occupied space. Windows perform valuable functions. They provide natural light, a view to the outside and, in many cases, a natural source of ventilation.