The sash is every part of a certain type of window that holds the glass in place. The sash also refers to the framework into which the panes of glass have been mounted. Today, the sash is usually just referred to as the window, but like the other components of this traditional window design, there are specific names for parts of the window that are useful to know when dealing with professionals in the windows and home design industries.
The sash stile refers to the vertical pieces outside the frame of the sash window. The panes of glass and the dividers into which the panes of glass fit all connect with the sash stile.
Head or Head Jamb
Situated across the top of the frame of a sash window is a piece of wood, metal or plastic. This component may be referred to as a head jamb, header or just plain head.
Upper and Lower Sash
The upper sash is the top window frame when speaking of a double-hung window. The lower sash refers to that window section located on the lower window frame. Not all sash windows have upper and lower sashes.
old window image by Alexey Klementiev from Fotolia.com
The pieces that divide the individual panes of glass within a sash frame have a special name: Muntins. Muntins may be constructed of wood or plastic and can be arranged vertically, horizontally or in a decorative pattern. Muntins originally had a functional purpose when window glass was available only in small sizes. Today, muntins very often do not actually divide individual panes of glass at all, but are overlaid on one large pane of glass for a decorative effect.
The meeting rail is also sometimes called the checkrail. It is the horizontal rail located at the bottom of the upper sash and the top of the lower sash on a double-hung window. To ensure a snug fit between the upper and lower sashes, the meeting rails are often bevelled.
The piece of wood, plastic or metal placed on the side, against which the sash window is able to slide up and down, is known as the stop. The stops are designed to be very sturdy. Removal usually involves a utility knife to cut through paint and a pry bar for the actual removal. This removal facilitates servicing of the sash window.
The sill of a sash window is a horizontal piece of wood, plastic or metal at the bottom of the frame. The outside part of the sill is typically slightly slanted to allow rainwater runoff. The sills often extend farther out from the sash window than any other component.