How do Sash and Case Windows Work?

Sash and case windows consist of two glazed timber-framed components, the 'sashes', which slide up and down in channels in the surrounding 'case'. The channels are formed by the case and two strips of timber called the 'baton rod' and 'parting bead'. Sashes are usually hung on ropes called 'sash cords', or occasionally on brass chains, which pass over pulleys in the top of the case.

The sash cords are connected to lead or iron counter weights hidden within the surrounding case. These weights counter-balance the heavy sashes, making it easier to open and close them, whilst also enabling the sashes to safety stay open in any position.