Sash windows are a traditional window style made up of one or two sliding panels, known as sashes, that move vertically within the frame. Commonly found in period and heritage properties, they are valued for their balanced proportions, simple operation, and ability to provide effective ventilation. Sash windows can be made from timber, uPVC, or aluminium and may include features such as counterweights, spring balances, and glazing bars. When properly maintained, they offer long service life, good airflow control, and a classic appearance that suits both older buildings and modern designs inspired by traditional architecture.