Upper sashThe top of the two sliding panels. It runs in the outer track and slides down.
Lower sashThe bottom of the two sliding panels. It runs in the inner track and slides up. In a double-hung window both sashes move.
Meeting railsThe upper sash's bottom rail and the lower sash's top rail. They meet in the middle when the window is shut.
PanesThe panes of glass. This window is six over six: six panes in each sash, the classic Georgian and Victorian pattern.
Muntins (glazing bars)The thin wooden bars that divide each sash into small panes. Also called glazing bars.
Sash lockA catch on the meeting rails that keeps both sashes tightly shut.
Sash cordA braided cotton cord, or a chain, tied to the sash's side. It runs up over the pulley and down to the weight.
PulleyThe sash cord runs over it. A small wheel near the top of the frame.
Sash weightsHeavy cast-iron, lead or steel weights hidden in the frame. They balance the weight of the sash, so it is easy to slide.
Weight pocketThe sash weights hang in it, out of sight. A hollow box in the side of the frame.
Parting beadKeeps the two sashes apart. It also holds the upper sash in its track. A thin strip set into a groove in the middle of the jamb.
Interior stopHolds the lower sash in its track. The strip on the room side of the frame. It is pried off to take the lower sash out.
SillThe bottom of the window frame. Water collects and decay often begins here.
How this list was compiled: Read 2026-09-27. (1) Wikipedia, Sash window, https://en.wikipedia.org/wiki/Sash_window : sashes, a double-hung window has two sashes that both move up and down, six over six as the classic arrangement, the sash weight of steel, lead or cast iron in the frame, the braided cotton sash cord or chain running over a pulley at the frame's top, muntins or glazing bars. (2) US National Park Service, Technical Preservation Services, Preservation Brief 9: The Repair of Historic Wooden Windows (John H. Myers), https://www.nps.gov/tps/how-to-preserve/briefs/9-wooden-windows.htm (archived copy, 2020): upper and lower sash, meeting rails, muntins, sash cords, sash weights, weight pocket, parting bead set into a groove in the centre of the stile, interior stop pried off to remove the lower sash, sash locks installed on the meeting rail, sill, jamb. Licence: own work
The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work
How it works
These are the parts of a double-hung window, the sash window of older houses, where both sashes slide. The first view opens the frame to show the cord and weight; the second cuts across it.
Read the full guide
Why a sash stays put
Each sash hangs from sash cords that run over a pulley near the top of the frame and down to a sash weight in the hidden weight pocket. The weight balances the sash, so it slides easily.
The two tracks
The upper sash runs in the outer track and the lower sash in the inner one. The parting bead keeps them apart, and the interior stop holds the lower sash in. Shut, they meet at the meeting rails, where the sash lock is.
To take out the lower sash, pry off the interior stop. The upper sash comes out after the thinner parting bead.
Questions and answers
What is the difference between single-hung and double-hung windows?
In a double-hung window both sashes slide up and down. In a single-hung window the upper sash is usually fixed and only the lower one moves.
What is a parting bead on a window?
A thin strip set into a groove in the middle of the jamb, between the two sashes. It holds the upper sash in its track.
What are sash weights made of?
Usually cast iron, lead or steel. Each hangs on a sash cord, a braided cotton cord or a chain, inside the frame.