Homeowners who are looking to enhance the aesthetic beauty and overall efficiency of their properties often opt to replace their windows and sliding doors. Windows are also a primary consideration when customizing new construction or restoring old units. Currently, an all new appreciation is growing for the classic, box sash window. Far more intricate than basic, modern designs, these carefully crafted units can give homes a timeless appeal. Following is everything you need to know about the history of box sash windows. A sash window is a window that slides vertically and that has a counter-weighted mechanism that facilitates the sliding. The very first vertical window designs are believed to have been introduced in the 1600s in France, however, the counter-weighted mechanism is a development that has been attributed to the British. The major benefit of this design at the time of its inception was an increased ability to increase and control indoor ventilation. This was possible given that the bottom and top sash frames had the ability to move independently of one another. Although people appreciated this functionality of these early window designs, there were some aspects of these products that served as serious fire hazards in certain situations. This will the case when the window frame was too close to the outside portion of the wall. As such, legislation introduced in Westminster and London during the 1700s declare that window frames and door frames could not sit any closer than nine inches to the wall. As such, the sash window invariably evolved. This legislation meant that a large majority of decorative frames were ultimately hidden by an exterior wall. Within two decades, however, the amended build was all the rage.