singlehung

A single-hung window is a type of sash window that has two vertically sliding panels, but only the lower sash is operable. The upper sash is fixed in place, while the bottom sash moves up and down to provide ventilation. This distinguishes single-hung from double-hung windows, where both sashes are operable.

Single-hung windows are commonly built with a variety of frame materials, including wood, vinyl, aluminum, and fiberglass. Glazing can range from single-pane to double- or triple-glazed units, often with energy-efficient options such as Low-E coatings or gas fills. Hardware and balance mechanisms vary by era and material; older wood versions may use a weight-and-pulley system, while modern vinyl and aluminum-framed units typically use integral balance systems or springs.

Advantages of single-hung windows include lower initial cost, simpler hardware, and compact profiles that can suit traditional architectural styles. They are generally easy to operate and require less maintenance than some other sash configurations. Limitations include restricted ventilation compared with double-hung windows, since only the bottom sash opens, and potential accessibility or egress considerations in bedrooms or other required spaces, depending on local building codes.

Installation and maintenance focus on proper sealing and weatherstripping to limit air leakage, regular cleaning of tracks, and periodic checks of balance hardware. Single-hung windows remain a popular economical option for both new construction and window replacement in a wide range of residential designs.