A window may seem like a very simple piece of equipment. While there are certainly more complicated devices in our modern world, a closer look at windows reveals that there are actually quite a a few more parts than you might expect. A window has to meet several design requirements, including the ability to let in light, and the outside view, while keeping the whether out. It needs to protect the interior from the outside rain without allowing it to leak through, and it needs to block heavy winds. To handle all of these requirements, windows actually have many parts and a surprising level of complexity.
One of the most common types of windows is the double hung window. The double hung hardware consists of two windows, an upper and a lower window. These windows can be slid up and down in the tracks located in the sides of the window. The double hung window parts include the jambs, the frame, the casing, and the sashes.
Double hung window parts can be made from wood, aluminum, vinyl, and in some cases a mixture of two or more of these materials. When choosing between materials for your double hung hardware, wood may be chosen for its more organic appearance as well as its property as being the best insulator against heat and cold. Alternatively, aluminum and vinyl require less maintenance, are more sturdy, and in some cases they may clash less with the look of the rest of the house.
Some windows will have a different set of double hung window parts than others. The pieces of the window that can be slid up and down are each called a sash. The trim along the top and bottom of each sash is called a rail. The trim along the side of each sash is referred to as a stile. Sashes are typically divided into several panes of glass, usually six of them. Each pane of glass is separated by a muntin. In some cases, the muntins really do separate individual pieces of glass. In other cases, there is only one pane of glass in each sash and the muntins are just decorative snap in pieces. Windows with decorative muntins rather than real ones are usually less expensive and easier to maintain, although they don't look as nice. The sash can be locked in to place using a sash lock.
The rest of the double hung hardware includes the jambs, frame, and casing. The jambs prevent air and water from leaking through the window. The sashes slide up and down through tracks located in the side jambs. The jamb on the top of the window is called the head jamb. The casing is used to hold the sashes in place. The frame is decorative. The bottom of the frame includes the window sill (which is the surface facing upward), the stool which protrudes outward, and the apron which sits below the stool.
As you can see, windows consist of quite a few double hung window parts. It is important that all of these parts are designed to work together and built with quality in mind in order to have a window that provides a good view and protects you from the elements.