Sash windows don’t open on a hinge. They are vertically opening windows generally associated with traditional and older properties.
A sash window consists of two framed windows – one is positioned in front of the other. This is more generally referred to as a sliding sash window. These windows units sit in frames with vertical grooves that allow them to move up and down smoothly without any danger of one frame rubbing against the other and damaging it. The up and down movement of the sashed is assisted by counterbalances – weights on cords and pulleys. These counter balances can be hidden within the frame or exposed on the inside of the window.