Window Spacer Types

Window Spacer Types

Window spacers have a big impact on how windows exist in your home. There are several types of window spacers that vary between metallic and non-metallic materials. Even among those groups, the materials used to create window spacers can vary so you need to understand what these types are and how they function. 

Let’s look at some of the more well-known types of window spacers, their functions, and how they can impact your windows.

What is a Window Spacer?

Window spacers are materials that are used to hold glass in place between window panes. Additionally, window spacers also help keep a tight seal around the edge of the glass panes. A tight seal improves the efficiency of windows by preventing the escape of insulating gases (krypton or argon) from escaping. Window spacers are made up of many different materials, with the main difference being that some are made of metal while others are non-metallic.

Image Credit: Diagram from Ernest Orlando Lawrence Berkeley National Laboratory, p. 12-3

Stainless Steel Window Spacers

Considered a ‘less metal’ window spacer, stainless steel window spacers are known as some of the strongest available. They are designed to ensure a tight and secure seal, allowing the window to retain insulating gas very well. As a result of the seal, stainless steel spacers are harder to see than other spacers making them a great in contemporary and high end windows. 

Aluminum Window Spacers

Though they are quite common, aluminum window spacers aren’t usually recommended because of the way the metal affects the glass surface. Aluminum is not an efficient material in windows because it expands and contracts in response to the weather. Too much expansion and contraction can cause seal failure. Seal failure cause:

  • Condensation between the window panes
  • Mold as a result of moisture build up
  • Stress cracks

Foam Window Spacers

Whereas aluminum window spacers can result in condensation and potential mold, foam window spacers are designed to prevent any of those cases from occurring. Foam window spacers are among the most effective window spacers, but don't have the durability or longevity of metal window spacers

Tin-Plated Steel Window Spacers

Another metallic material used for window spacers is tin-plated steel. Tin-plated steel spacers were designed as an alternative to aluminum spacers. The stainless steel alloy creates a thermal barrier against heat loss and the shape of the spacer flexes to resist seal failure. 

Vinyl Window Spacers

When vinyl is used as a window spacer, is it one of the many materials that can be used to reduce the transfer of heat. Like other non-metal window spacer materials, though, there is potential that this material could emit gas when exposed to heat, working to create a foggy space between the panes that can make it difficult to see through the window..

Rubberized Window Spacers

Through “Warm-Edge” testing, it’s been found that window spacers made of non-metal materials (like rubberized) will help your windows feel warmer from the inside of your home, which improves the warm feeling and protection you want out of your windows. However, one of the limits here is that rubberized window spacers aren’t as malleable as the metal materials which could make it difficult to shape according to your needs.

Image Credit: Diagram from Ernest Orlando Lawrence Berkeley National Laboratory, p. 5

Regardless of which material you choose, it’s important to know the many types of window spacers to make sure your window panes are being protected in the right way and with that right type. Every part of your window is important and knowing your goals for your windows will help you determine what window spacers will benefit you most.

Diagram Source: 

SINTEF Building and Infrastructure, Norwegian University of Science and Technology, Bergh, Sofie Van Den, Hart, Robert, Jelle, Bjrn Petter, & Gustavsen, Arild. Window Spacers and Edge Seals in Insulating Glass Units: A State-of-the-Art Review and Future Perspectives. United States.


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