why every sash window is unique and hand made/custom made

Sash windows are available in many styles and and sizes and this is not a coincidence, sash windows are mostly used in city town houses helping to keep cool air flowing in the bottom of the window

while hotter air flow out the top, as cities tend to be warmer than urban areas.
The history of cities and its architectural influnce scales back many hundreds of years, not surprisingly. Even today many homes that are refurbished and built the owners and architects like to

vary their style, all this adds up to why almost every home would have unique window measurements. It doesn't stop there as most windows also need to match the architectural style of the building

and design choices. Whatever your building or design choices for your property woodstock joinery have a workshop for building bespoke joinery and box sash windows.