Sliding Sash Windows, Fashions and Variations
Fashion and regional differances propagated many variations. As well as old windows being updated in full or part. For example an early 12 over 12 could be up graded to 12 over 1.
12 over 12 sash upgraded to 12 over 1
Late in the 19th century we also had revial of earlier 200 year old styles.
Mix and Match 1885 new build Sliding sash
Many decorative styles with fancy variations of glazing bars have been used to show off and enhance the look of buildings.
Window Styles and Details to make an Impression
However the basic principle of the sliding sash has remained the same.
If there's anything I might have missed, please leave me a comment.