Tempered glass

Tempered glass in a squash court

The strong choice

Guardian tempered glass is ideal when building codes or design specifications require safe solutions. Tempered glass is four to five times stronger than annealed glass, and breaks into fragments that are less likely to cause serious injury. Whether it's applied to storefronts, fire knock-out panels or fireplaces, Guardian tempered glass can provide peace of mind.

How it's made

Producing tempered glass involves heating the glass to over 1,000 degrees F, then rapidly cooling to lock the glass surfaces in a state of compression and the core in a state of tension.

Bring on the wind loads and thermal stress

Guardian heat-strengthened glass is the preferred choice for projects where safety glass isn’t required, but resistance to wind and heat is key. Heat-strengthened glass is cooled at a slower pace, creating glass twice as strong as annealed glass. When broken, the fragments are larger than tempered glass but are less prone to spontaneous breakage. Our heat-strengthened glass is an excellent choice for projects using tinted, reflective, low-E and spandrel glass—options all available through Guardian SunGuard® coated glass.

Reduce the risk of spontaneous breakage

Guardian heat-soaked glass helps avoid unpredictable breakage caused by nickel sulfide (NiS) inclusions. All float glass contains these invisible imperfections that can increase in volume over time and cause stress to tempered glass. The Guardian heat-soaking process exposes NiS inclusions in tempered glass, then breaks them safely in a heat-soak chamber before the glass reaches the field.

Guardian SunGuard® coated glass can be safely heat soaked if it is determined the heat-soaking process is necessary. Explore our SunGuard coated glass below.

Improve security, safety and comfort

Guardian tempered glass can be combined with numerous ClimaGuard® residential glass and SunGuard® coated glass solutions.

Guardian Glass - ClimaGuard - 80/70 - man and daughter playing

ClimaGuard 80/70

ENERGY STAR® Northern Zone

Selectively lets visible light in to brighten and warm northern homes naturally, and provides insulation to stop heat from escaping

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Guardian Glass - ClimaGuard - 72/57 - man listing to music, snowy landscape and mountain outside window

ClimaGuard 72/57

ENERGY STAR® Northern and North-Central Zones

Provides ample light, solar heat gain and retains heat indoors in climates with cold winters

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Guardian Glass - ClimaGuard - 53/23 - photo of young African America woman reading on sofa with glass of juice

ClimaGuard 53/23

South-Central and Southern ENERGY STAR® Zones

Cools homes in warm, southern climates with triple silver protection to lower solar heat gain and U-value

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Guardian Glass - ClimaGuard - IS-20 - a group of friends playing a game

ClimaGuard IS-20


Enhances performance by lowering U-value of standard low-E windows to help meet energy codes

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Guardian Glass SunGuard - Hearst Corporation building


High-performance architectural glass that helps architects and designers Build With Light®.

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SunGuard Select Fabricators

SunGuard Advanced Architectural Glass is designed so it can be tempered by our network of independent SunGuard Select Fabricators. Our fabricators can help heat treat glass more quickly and closer to your project site for faster replacements and shorter lead times.