Guide to the Terms for Different Parts of a Window

Understanding the various parts of a window is essential for homeowners looking to replace or repair their windows. Knowing the names and functions of different window parts can help you make informed decisions and communicate effectively with window contractors and professionals. In this guide, we’ll explore the anatomy of a window, focusing on key terms and their importance in replacement window projects. 

Head Jamb 

The head jamb is the top horizontal piece of the window frame. It supports the upper part of the window and provides structural stability. When considering replacement window parts, the head jamb is a critical component to ensure a secure fit and proper alignment. 

Grilles Between the Glass (GBG) 

Grilles between the glass (GBG) are decorative elements that give the appearance of divided panes without the hassle of cleaning around individual grilles. This feature enhances the aesthetic appeal of your windows while maintaining ease of maintenance. GBG is a popular choice among homeowners who want to combine style with functionality. 


The glazing, or glass, is the most prominent part of a window. Modern windows often feature double or triple glazing to improve insulation and energy efficiency. The type of glass used can significantly impact your home’s energy performance, noise reduction, and security. Energy-efficient glass windows are a smart investment for homeowners looking to reduce energy costs. 

Window Sash 

The sash is the part of the window that holds the glass panes in place. In single-hung and double-hung windows, the sash is movable, allowing the window to open and close. The sash consists of several other parts, including the stiles and rails, which provide structure and support. 

Side Jamb 

The side jambs are the vertical pieces on either side of the window frame. They support the sash and hold the window in place within the wall. Properly installed side jambs are crucial for the window’s stability and smooth operation. 


Stiles are the vertical components of the window sash. They run along the sides of the sash and connect to the rails, forming the framework that holds the glass. Understanding the role of stiles is important when discussing replacement window parts, as damaged or warped stiles can affect the window’s functionality. 


Rails are the horizontal components of the window sash. There are typically two rails: the top rail and the bottom rail. These rails connect to the stiles and help form the structure of the sash. The bottom rail often features a lock to secure the window when closed. 

Window Sill 

The sill is the bottom horizontal piece of the window frame. It supports the window and helps to direct water away from the wall, preventing moisture damage. The sill is an essential part of a window frame that contributes to the overall durability and weather resistance of the window. 

Single-Hung and Double-Hung Windows 

Single hung and double hung windows are common window types that differ in how the sashes operate. In single hung windows, only the bottom sash moves, while the top sash remains fixed. In double hung windows, both the top and bottom sashes are operable, allowing for improved ventilation and easier cleaning. 

Vinyl Window Parts 

Vinyl windows are a popular choice due to their durability, energy efficiency, and low maintenance. Vinyl window parts include frames, sashes, and grilles, all made from polyvinyl chloride (PVC). These parts are resistant to moisture, warping, and pests, making vinyl windows an excellent long-term investment for homeowners. 

Get Started with Expert Replacement Window Installers 

Understanding the various parts of a window can help you make better decisions when it comes to window replacement and maintenance. At Morgan Exteriors, we offer a wide range of high-quality vinyl windows and other replacement window parts to meet your needs. Whether you’re looking to improve energy efficiency, enhance aesthetics, or increase home security, our expert team is here to guide you through the process. 

Ready to upgrade your windows? Contact Morgan Exteriors today for a consultation. We proudly serve homeowners in Tampa, Orlando, Fort Myers, Jacksonville, Lutz, and surrounding areas. Let us help you enhance your home’s beauty, comfort, and energy efficiency with our top-of-the-line window solutions.

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