What Is a Single Hung Flange Window?

Window Anatomy

• Windows are held into place with sashes, frames and flanges. The window pane, the actual transparent portion of the window, is called the glazing. The glazing is seated within a window's sash where it is held in place by caulk, glue or, in the case of vinyl windows, a seam. The sash is the portion of the window that moves up or down, or side to side, and allows the window to open. Sashes move along grooves, or tracks, within the window frame. The window frame is surrounded by a lip, or flange. This portion is essential to window installation but is normally not visible when construction is complete.

Installation

• The window's frame is seated in a prepared opening in a building's wall. This opening is referred to as the rough opening. When placing a window into the rough opening, window contractors must affix the frame to the building's exterior by nailing the flange to the building. This must be done with care to ensure that the window has a tight seal and is impervious to leaks. After the flanges have been attached to the building, contractors must place flashing over the area to maintain a seal. Siding is placed over the flashing leaving no trace of a rough opening.

Double and Single Hung Windows

• Double hung windows feature two movable sashes; both the upper and lower portions of the window open and close. Single hung windows feature only one movable sash. The other portion of the window is fixed. The movable portion of the window can be cranked open -- as often found in smaller kitchen or bathroom windows. Single hung windows are more economical than double hung windows but they can be more difficult to clean.

Considerations

• Flanges, or fins, are one method used to attach windows to a structure. Fins are also called integral fins and are considered an appendage to the window. Some windows do not feature attachments. These windows, called non-fin windows, block windows or box windows.