A window sash is the framed section of a window that holds the glass. In a traditional sliding sash and case window, the sashes move vertically within the surrounding fixed timber case. The sash and the case are different components, although the terms are often confused.
What is the sash on a window?
Think of the sash as the moving glazed panel. Its timber rails and stiles form a frame around the glass. Many traditional Scottish sash and case windows have two sashes: an upper sash and a lower sash. Depending on the design and condition, one or both can slide to provide ventilation.
What is the difference between a window sash and frame?
The sash holds the glazing; the case is the fixed outer frame fitted into the building opening. The case provides the channels and space for the sashes to slide, and often accommodates the concealed weights and pulleys.
Parts of a traditional sash window
- Top and bottom rails: horizontal timber members of each sash.
- Stiles: vertical sides of the sash.
- Meeting rails: where the upper and lower sashes meet when closed.
- Glazing bars: smaller timber members dividing panes in some traditional designs.
- Sash cords and pulleys: allow many traditional sashes to travel smoothly.
- Counterweights: concealed weights that balance the sash.
- Fasteners and stops: fittings that secure or limit sash movement.
How does a sash move?
In a traditional cord-and-weight system, cords run over pulleys and connect the sash to counterweights within the case. The weights offset much of the sash’s mass, helping it stay in position. Other designs use spiral balances rather than cords and weights. Learn more in our spiral balance guide.
Can a damaged window sash be repaired?
Often, yes. Localised decay in a rail or stile may be repaired with appropriately matched timber where the remaining joinery is sound. Failed cords, sticking sashes, damaged putty and loose joints can also be addressed without replacing the entire window. See our sash and case window repair service and window restoration options.
Can you replace just the sash?
Sometimes the existing case can be retained while a badly damaged sash is replaced. Suitability depends on the condition and dimensions of the case, glazing requirements and any conservation restrictions. An inspection helps determine whether repair, a replacement sash or wider restoration is appropriate.
Common questions about window sashes
Is a sash the same as a window pane?
No. The pane is the glass; the sash is the frame that holds it.
Why does my sash window rattle?
Wear, excess clearance, loose fittings or failed seals may cause rattling. Carefully specified draught proofing can often improve comfort.
What keeps a sash window shut?
A sash fastener at the meeting rails commonly secures the closed sashes. Other suitable security fittings can supplement it; see our security and ironmongery service.
Related guide: sash and case windows
For a wider explanation of the whole window assembly, read What Is a Sash and Case Window?. If your timber windows need attention in Scotland, request an assessment and quotation.