A Guide to Window Terminology

As you shop for new windows, you will run into a lot of terminology that may seem foreign. But while you don’t have to be a window expert to choose good windows, you should know what to look for and what design elements you want.

To help you find the perfect look and efficiency, read this short guide to some basic window terms and functions.

The Frame

Each window is made of two parts: the frame and the sash. The frame is what attaches to the walls around the window. Frames generally consist of three parts:

  • The head. This is the top unit in the frame. It’s usually horizontal but may also be arched or diagonal. It can also be referred to as a head jamb.
  • The jambs. Jambs are the side pieces of the frame. Side jambs, as they are sometimes called, are usually vertical but can be other shapes in unique windows.
  • The sill. The most common term is the window sill. The sill is the horizontal piece along the bottom. It is often wider than the jambs.

Frames are usually made of the following materials: vinyl, wood, fiberglass, aluminum, or Fiberex. Each material has pros and cons. Which material is best for you depends on how energy-efficient and low-maintenance you want your window to be.

The Sash

The operating portion of the window is called the sash. The sash is made of these basic parts:

  • The stiles. These are the vertical pieces that hold the glass in place.
  • The rails. The rails are the same as the stiles, but horizontal.
  • The panes. The glass itself is often described in terms of how many pieces are hung together as a unit. Double-pane windows feature two panes of glass set into the sash with a pocket of insulating argon gas between them. Triple-paned windows have three panes for more energy efficiency. Different coatings can be applied to the panes to help with energy efficiency too.
  • The grills (optional). The sash may have additional material between the glass to give another decorative detail. Grills come in different styles, including colonial, prairie, and diamond. You can also choose to have applied grills, which give the grills a more defined look.  Many people choose to have interior removable grills. These grills give you flexibility to take out the grills for an unobstructed view.

Speak with a window expert to learn more about your options for how your windows look and function.

Energy Efficiency

You’ll likely want a very energy efficient window with an Energy Star certification. Double-pane and triple-pane windows are more popular for their energy saving layers. But there are some other factors.

You will also hear about U-value and R-value. R-value measures resistance to heat flow and therefore energy blockage. You want a higher R-value. U-value is the measure of heat transfer. For U-value, you want a lower number.

Energy efficiency ratings also often include the idea of low-E windows. This stands for low emissivity, and it’s a reference to the amount of natural radiation that passes through the glass and heats up your home. There are two methods for coating glass to produce this effect, called soft-coat low-E and hard-coat low-E glass.

Types of Windows

Window design may not be at the forefront of your mind when you think of your home, but these architectural features can be quite varied according to what you want them to do.

Stationary windows, for example, do not open. They are decorative and often found in less-accessible places like attics, stairways, and halls. Similarly, a transom window lets in additional light and design interest above a door or window. Transom windows can be a couple different shapes, including rectangles, half-rounds, arched, or eyebrow. Bay and bow windows extend outward to provide more space inside.

Many windows are also described by how they move. Here are some examples:

  • Casement. The sash swings out from the left or right side.
  • Awning. You can crank the windows to swing out and upward from the center.
  • Single-hung. Either the top or the bottom sash moves up and down along the jambs. Typically, the top sash is fixed and the bottom sash operates.
  • Double-hung. Both sashes operate by moving up and down along the side jambs.
  • Gliding.  These windows have two sashes side by side. The left or right sash moves horizontally along the jambs.

To learn more about the basics of window choice and how to decide what’s right for a particular spot in your home, contact JFK Window & Door Co. today.

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