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There are many kinds of windows, but nothing’s better for your fenestration vocabulary than learning the names of the parts of the most common window style — the double-hung. Now you can talk the talk!
Let’s start from the top. The header is the top horizontal piece of the frame. The jamb refers to the vertical side pieces of the frame. The sill is the horizontal part at the bottom of the frame. (Looking at the window from outside, you’d see the stool where the sill is, often supported by a small board called an apron.)
Now let’s get to the real business of this window. Double-hungs have two moving pieces, called the sash. The piece on top is the upper sash, which can be lowered from its closed position, and on the bottom is the lower sash, which can be raised. The rails are the horizontal part of the sash frame and the stiles are the vertical parts.
The sash, upper and lower, hold the glass portion of the window. A single piece of glass is called a pane. A sash can have one or more panes; the dividers between the panes are called muntins. On both vertical sides of the sash are channels, which guide the sash up or down in a straight line. The small molding piece that runs up the front, at the sides of the lower sash is called the inside stop, which keeps the sash running smoothly in its channel. The sashes lock together by means of a two-piece latch, positioned atop the upper rail of the lower sash, and the bottom rail of the upper sash.
If your windows look like double-hungs, but the upper sash doesn’t move, these are called single-hung windows.
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