Insulating Glass Sealants

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For a properly constructed Insulating Glass Unit (IGU), two sealants are required: a primary seal that is an excellent moisture barrier and a secondary seal that provides structural integrity. The best sealant for a particular application depends on factors like UV exposure, temperature fluctuations, and project requirements.

Primary sealants

This sealant is applied between the spacer and the glass to create a moisture-proof seal and prevent the escape of any insulating gas, such as argon.

  • Butyl Sealant: A hot-applied sealant that offers excellent resistance to moisture vapor and gas transmission.
    • Recommended product:

      Hot Melt Butyl is available in chunks for use with a bulk hot-melt applicator system, such as those from Hot Melt Technologies.

Secondary sealants

The secondary sealant is applied after the primary seal to provide structural strength and protect the unit from weather, UV exposure, and temperature changes. The best option for this application depends on your specific use case.

For structural glazing and high-performance applications

Structural silicone sealants are required by industry standards for curtain walls and other applications where the seal carries a structural load.

  • Sikasil® IG Silicone Sealants: Manufactured by Sika, these two-component silicones offer excellent UV stability and are approved for structural glazing facades.
  • EdgeSil™ IGS3723 Sealant: This two-part silicone from Momentive provides high strength and adhesion, making it ideal for the edge seals in structural and non-structural IGUs.
  • J2400 Single-component Silicone Structural Glazing Sealant: Offered by Qingdao Joobond New Materials Co., Ltd., this product is designed for applications needing a high-strength, flexible, and weather-resistant bond.

For standard residential and commercial windows

For standard doors, windows, and open-frame curtain walls, you can choose from silicone, polysulfide, or polyurethane secondary sealants.

CRL Black Two- Part Polysulfide Insulating Glass Sealant

DK Hardware& more

A popular two-part sealant that offers high durability and adhesion to glass and aluminum. It is resistant to weather, ozone, and UV light.

  • Where to buy: You can purchase this product at retailers like CRL.

Pecora 896 FC 11oz Tube – Translucent

Metro Sealant

A one-part, neutral-curing silicone sealant from Pecora that offers quick adhesion and is specifically designed for the window and door glazing industry.

CRL Black Glass Silicone Sealant

DK Hardware& more

A one-part silicone sealant with UV inhibitors that provides excellent weather resistance and a long-lasting seal.

  • Where to buy: Available from retailers like DK Hardware.

Super Spacer 877 Insulating Glass Sealant

DK Hardware& more

This easy-to-use black silicone foam sealant from CRL is suitable for both glass and metal, offering excellent adhesion and water resistance.

  • Where to buy: Available at retailers like DK Hardware.

How to choose the right sealant

Selecting the correct insulating glass sealant depends on the specific demands of your project.

  • Consider the application: For standard windows and doors, silicones, polysulfides, and polyurethanes can all be used. For structural glazing, you must use a structural silicone sealant to ensure safety and performance.
  • Evaluate environmental conditions: Silicones generally offer the best resistance to UV light, high and low temperatures, and weathering. Polyurethane and polysulfide offer good weather resistance but are not as durable when exposed to sunlight for prolonged periods.
  • Check compatibility: Ensure the chosen sealant is compatible with the primary butyl sealant and all other materials used in the IGU construction.
  • Prioritize quality: A high-quality sealant is critical for the long-term durability and energy performance of an IGU. Using a low-cost, inferior sealant can lead to premature seal failure.
  • Ensure proper installation: The performance of even the best sealant can be compromised by improper application. Adhere to the manufacturer’s recommended application and curing procedures, including temperature and humidity requirements.
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