Crystal Clear: Learn the Terminology to Sound Smart When Talking About Windows

windows on exterior of home | Rolox Home Service

New replacement windows may make your outlook clearer, but the process of getting them may be confusing, full of questions and terms you’ve never heard before! We never want our customers to feel like they’re out of the loop regarding their window options, which is why we strive to provide complete transparency and clarity when discussing replacement windows by explaining the terms we use in detail. Still, it never hurts to be ahead of the game when your window installation team comes knocking!

Consider this your go-to dictionary for window terminology. It will help you sound knowledgeable when discussing all things windows — even if it’s just bragging about the phenomenal energy efficiency of your argon-filled windows with your neighbor.


Parts of a Window

Let’s start with what makes up a window. Many different components are integral to windows of all kinds, and just knowing these basic terms will set you up for success in future window-related chit-chat!

Window Frame Parts

The window frame is the vinyl, wood, fiberglass, or aluminum part that borders and supports the window glass. It is comprised of four different elements:


  1. Head: The uppermost horizontal part forming the top of the window frame.
  2. Sill: The lowermost horizontal part forms the window frame’s base, sometimes called a “window stool.”
  3. Jamb: The vertical parts on either side of the window frame
  4. Apron: A decorative trim installed below the sill of the window (sometimes mistakenly called the “window sill” by homeowners).

Window Sash and Glass Parts

The window sash is the part of your window that slides or tilts open to let in the fresh air, and it needs more than glass panes to be sturdy and reliable!


  1. Pane: This is the actual glass portion of your window. Your window pane may comprise multiple pieces of glass or one solid piece.
  2. Rail: The top and bottom components of the sash. Most windows have two rails, one on top and one on bottom. But double-hung windows have four (two on each end).
  3. Sash Lock: The locking mechanism that prevents your window sash from being opened, providing security against intrusion or escape-artist toddlers.
  4. Lift: The handle used to grip and lift the sash open.

Other Window Parts

Windows need more than a good sash and frame to work properly! Here are a few other key components every window tends to have:


  1. Weather Stripping: Positioned between the window frame and sash, weather stripping adds another layer of insulation by sealing up any extra space.
  2. Mullion: A structural piece used to connect multiple windows together.
  3. Balance: This is a piece often used on single or double-hung windows to hold them open wherever they are positioned along the slider.
  4. Grilles/Muntins: These materials give the illusion of multiple panes of glass.
  5. Screen: Here’s one you probably know! The screen is the mesh material that keeps pests out of your home when the window is open.


Types of Windows and Other Terminology

In addition to understanding the many parts that make up a window, you should be versed in the various types of windows and the window terminology unique to each type.


  1. Fixed Panel Window: Unlike a sash, which moves to open and close, fixed panels are window panes that don’t move. You’ll most frequently see these on single-hung windows or architectural windows that are not made to open.
  2. Single and Double-hung Windows: These are the most common window types found in homes today, and they have one key difference: Double-hung windows have two sliding sashes that can tilt inward for easier cleaning, whereas single-hung windows are composed of one sliding sash and one fixed panel.
  3. Casement Windows: Unlike their sliding counterparts defined above, casement windows open and close by rotating a lever to tilt the sash out and back in. They’re a popular choice for kitchen windows, especially when positioned over a sink or counter where sliding a window open could prove cumbersome! Here are a couple of casement window-specific terms to know:
  • Lock Handle: The locking mechanism on the jamb that provides greater security.
  • Operator: The technical term for the crank or rotating handle that opens and closes the window.
  • Storm Windows: In some regions, storm windows are popular for adding an extra layer of protection on top of your existing windows to keep them from getting damaged by inclement weather. These aren’t usually necessary if you have reliable and relatively new windows or live in a mild climate. Here’s one more bonus term for you:
  • Weep Hole: A weep hole acts as an outlet for water to drain out to prevent water or condensation from filling the gap between your storm window and permanent windows.


  1. Energy-efficient Windows: Energy-efficient windows have been designed to effectively insulate your home, helping maintain comfortable temperatures inside and keeping the heat or cold outdoor temperatures from penetrating. The best way to know whether your windows are energy-efficient is to look at their Air Infiltration ratings. You’re in good hands if your windows are Energy Star and NFRC certified! Here are a few more buzzwords to look for in relation to energy efficiency:
  • Window Film: This separate film can be applied to your window’s glass to reflect harmful UV rays and improve thermal efficiency.
  • Low-E Glass: Low-E or “low-emissivity” glass has a special coating designed to reflect thermal radiation (rendering temporary fixes like window film unnecessary!)
  • Argon Gas: This completely safe, inert gas fills the space between double-pane windows. It greatly improves energy and thermal efficiency! Some window manufacturers use Krypton or a blend of the two gases for a similar effect.


Ready to Talk Windows?

Now that you’re a bonafide window expert, you’re ready to start the conversation about how we can upgrade your home with beautiful new replacement windows! Whether you need a broken or faulty window replaced or are interested in improving your energy efficiency, Rolox windows are made to reflect only the best outcomes for your home’s future.


Schedule your free quote today!

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