How sash windows work
The top sash hangs on the outer side of the window and the bottom sash hangs on the inner side of the window. An equal weight balances the weight of the sash, and when done right, you can lift the sash effortlessly or;
The sash window slides up and down, which is the key differentiator. This type of window isn’t common in the rest of the world and is typically only found in British colonial countries.
The history of sash windows
This is a sketch of a sash window from an old joinery and carpentry book that was published in 1902.
Joiners who built all the period properties around London back then learned from books like these.
Over the years, many joineries and larger window companies have compromised along the way, and now make timber sash windows that are completely different to traditional sash windows. But they’re still calling them sash windows!