Sash windows are associated with the architecture of the 18th and 19th centuries. Their popularity stemmed from their larger panes of glass and more elegant proportions than casement windows.

Despite much debate, the sash window is now thought to have originated in Yorkshire, England. They were developed there to keep out wet weather while permitting air to circulate by leaving a narrow opening, and were also protected from rot and distortion by being closed in a box.

Sash windows offered both practical advantages and a more pleasing style than older window designs, and they were popular in both new buildings and as stylish replacements in existing homes. During the mid 18th century the introduction of the window tax caused many windows to be removed. The Georgian sash window took on the modern double sash form. Glass was still expensive and marked with central bull’s eyes by the manufacture process. As better methods of making large panes were found, windows with six panels in each sash appeared, becoming characteristic of the Georgian sash window. They became a key part of Regency architecture.

Sash windows continued to be popular during the reign of Queen Victoria, although carved and molded decorations were commonly added to them. Victorian houses often have large bay windows and elegantly proportioned facades with the windows getting gradually smaller as their height from the ground increases. Four paned sashes often indicate a Victorian style. Imitations of older style windows were also popular towards the end of the 19th century, as the wealthy sought to differentiate themselves from the previously prized plate glass and narrow glazing bars that had became more affordable.

Sash windows have become far less common during the last century, despite being the favorite style at the beginning of the 20th century, due to the increase in cheap, mass-produced styles of window. An interest in conserving historical styles of architecture has recently revived the demand for sash windows, however. Sash windows today use all the latest technology, but retain the elegance and functionality of traditional sashes, and preserve the historic style of the older houses.