Okay, windows are simple, right? It’s just glass, vinyl/aluminum, and sealant, right? Not really. There are many more parts of a window than just the glass and frame, especially if you’re getting a custom-made window with lots of added features like multiple glass layers, argon gas fills, and more.
A properly-made window is deceptively complicated. It looks simple from the outside, but will have a lot of critical components on the inside. A top window installation company can walk you through the parts of a window and explain why each is important so you can make an informed decision when selecting a custom window.
What are the parts of a window? Why is each part important? Let’s go over the list of window parts and explain each one so you know what to look for!
Parts of a Window: Frame Components
The first part of a window to discuss is the frame. The frame is what holds the window glass or sash in place and secures to the window opening. Window frames can be made from a variety of materials, such as aluminum, wood, vinyl, composite materials, or hybrid frames that combine different materials for different parts of the frame.
Frame Materials
The material choice for the frame can have a significant impact on the performance of the window in different categories.
For example, aluminum is a highly thermally conductive material, transferring 160 W/m*K of thermal energy. Meanwhile, vinyl (also known as PVC, or polyvinyl chloride) has a thermal conductivity of 0.17 W/m*K. In other words, aluminum transfers over 940 times as much thermal energy as vinyl does.
On the other hand, the tensile strength of aluminum varies between 80 MPa and 570 MPa (11,603 to 82,671.5 psi) depending on the alloy used, while vinyl has a tensile strength around 52 MPa (7,541.96 psi).
In Florida, windows need to be both durable and energy efficient, which is why vinyl is one of the most popular materials for hurricane windows. They have plenty of strength for resisting hurricane-force winds and insulate the home against outside temperatures extremely well.
Parts of a Window Frame:
The frame of a window has several major components to know:
- Frame Apron. An underhanging part of the frame that extends just below the stool.
- Frame Casing. The molding on the outside of the window that seals the frame to the house.
- Frame Head. This is the top part of the frame that runs parallel to the ground.
- Frame Jambs. These are the vertical sides of the frame that run from the head at the top to the sill at the bottom.
- Frame Sill. The bottom part of the frame on the exterior of the opening.
- Frame Stool. An interior ledge at the bottom of the window. Sometimes used as a shelf or decorative detail.
In addition to these frame components, a window’s frame may have various screws, plugs, shims, and more that help secure the frame of the window to your window opening and complete the seal from the inside.
Parts of a Window: The Sash
The sash is the part of a window that holds the glass. It also typically includes the components that allow the window to be opened and closed (for windows that can be opened and closed).
LIke the window frame itself, the sash of a window can be made of various materials. In many cases, the sash will be made from similar materials to the window.
The main components of a window sash include:
- Balance System. A mechanism in single- and double-hung windows that helps offset the weight of a window sash to make it easier to operate. Available in a variety of styles, such as pulleys, block and tackle systems, or springs, depending on the window type and manufacturer.
- Glass Panes/Glazing. The glass in the window set into the sash.
- Grilles. Decorative bars inside of the sash that modify the window’s appearance. Available in a variety of styles:
- True Divided Light. The grilles separate actual panes of glass.
- Simulated Divided Light (SDL). The grilles go over and under a single pane of glass to simulate the look of a truly divided glass pane.
- Grilles Between Glass (GBG). Grilles sealed inside two panes of glass. Provides the look without impeding cleaning and maintenance.
- Removable. Grilles that can be taken off or put on to make it easy to clean or to change the look to suit your preferences.
- Lift. A handle or similar device used to make it easier to move the sash by providing leverage.
- Rails. The horizontal parts at the top and bottom of a sash.
- Stiles. The vertical pieces at the sides of a sash.
- Sash Lock. Hardware that holds the sash in place. The appearance and mechanisms involved may vary from one type of window to the next. Not included in non-openable windows.
- Sash Stop. A stationary part of the window that stops the sash from moving too far in one direction or another.
About Glass Panes:
Windows can have one, two, or three layers of glass panes depending on the style and manufacturer. Single-pane windows tend to provide weaker insulation and protection than double- and triple-paned glass windows.
When windows have multiple panes of glass, they may also have more components between the glass panes to further enhance their insulating properties. For example, a double-paned window might have an argon gas fill to further inhibit heat transference and a butyl sealant to prevent the argon gas from leaking.
Multi-paned windows will also have spacer bars separating the panes of glass to create added space to enhance its insulation.
How the Parts of a Window May Vary By Type
Not all windows are the same. Different types of windows may have different parts or may completely lack certain parts.
For example, picture windows are fixed in place, meaning that they don’t have moving parts. So, they don’t need sash stops, locks, lifts, or balance systems.
Meanwhile, casement windows don’t use pulleys or other balance systems. Instead, they have cranks or multi-point locks. Awning windows also often use cranks for their opening mechanisms or have an armature (sometimes called an operating arm) that keeps them in place when open.
Single-hung windows have one “fixed” (i.e., non-moving) sash and one movable sash. Meanwhile, double-hung windows have two moving sashes, which each will have separate locking mechanisms, lifts, etc.
Horizontally-opening windows may have rollers rather than pulleys or other balances to make opening them easier.
Additional Parts of a Window to Know About
There are more parts of a window to consider when ordering a new one for your Florida home. Some of these parts may be optional add-ons while others may be mandated by the Florida Building Code (FBC). A few are critical pieces of the window’s installation that aren’t necessarily a part of its frame or sash:
Cladding
Some manufacturers may add an additional layer of material to cover the outside of their window sashes and frames. This layer is called cladding and help protect the underlaying material from direct impacts.
For example, some manufacturers may add a layer of aluminum over wood or vinyl windows to increase the window’s durability without sacrificing its thermal resistance.
Drip Caps
A piece of material that is added to the top of a window frame to let water run off the casing rather than seeping into or around the casing and into your home.
Mullions
Mullions are a part to fill the gap between two connected windows that are in a larger window opening, helping stabilize the two windows.
Nailing Fins/Mounting Flanges
These are thin strips of material that go around the edge of a window frame and can help hold it in place during the installation of shims and screws. Post-installation, these flanged surfaces can also form part of the window’s “weather resistant barrier” that helps keep out water and wind.
Screens
Screens mount on the exterior of a window to help keep out pests and debris when the window is open. The fine wire mesh in window screens is often made of fiberglass or metal materials to ensure long-term durability.
Sealant
During the window installation process, a sealant may be added between the edges of the frame and the opening to create a stronger seal and improve the window’s insulative quality.
Shims
Shims are thin strips of material used to help hold a window in place and level while the window is being installed. They go between the window frame and the rough opening and help prevent warping or excessive movement that negatively impact the window’s installation.
Weatherstripping
This is material added around a window frame and/or sash to provide extra protection against extreme weather conditions.
Window Opening Control Devices (WOCDs)
These are safety devices that limit how wide a window can be opened, typically used to prevent children from opening and falling out of the window. The Florida Building Code specifies WOCDs as one of the required controls in “Group R-2 and R-3 buildings including dwelling units, where the top of the sill of an operable window opening is located less than 36 inches (914 mm) above the finished floor and more than 72 inches (1829 mm) above the finished grade or other surface below on the exterior of the building.”
A WOCD should prevent a window from opening more than 4 inches wide to prevent the risk of falling injuries among small children.
Get All the Parts of Your Windows Expertly Installed
Looking for a new window for your home? Make sure each window has all the parts of a window that they should have by working with a top-quality installer using windows made by the best manufacturers in Florida.
Reach out to Karoly Windows & Doors today to request an in-person installation consultation where one of our experts will walk you through your replacement window needs and how to pick the best windows for your home.
