UL is a globally recognized safety science brand that provides standards and testing protocols that are relevant to a huge array of different industries. In the bullet-resistant glass field, the most relevant UL testing standard is UL 752. That is the specific protocol that is often referenced when someone mentions “UL-rated windows.” 

Shattered UL rated bulletproof window

UL 752 includes products that fall into several different levels of ballistic protection. If you’re designing or upgrading a building that may require bullet-resistant doors or windows, it helps to have at least a basic understanding of the types of protection that UL-rated windows can provide. Then you can work with a trusted bullet-resistant glass supplier to find the specific materials and designs that suit the needs of your facilities.

For now, here are answers to some of the most common questions that building owners and designers have about UL-rated windows.  

What Are the Different UL Fire-Rated Windows?

UL 752-rated windows fall into eight different levels based on what type of ballistic protection they provide. Each one is tested against a specific type and amount of ballistic impact, down to the exact speed a bullet must be traveling as it strikes the glass. 

In order to qualify for any UL 752 rating, a product must experience no spall when struck with the relevant ballistics. So if any glass spalls to the safe side of the window penetrating the cardboard witness shield, the product would not be able to use this labeling designation.

Here’s a quick rundown of the various UL 752 levels. 

  • Level 1 protects against three shots of a 124-grain 9mm full metal copper jacket with lead core at an FPS between 1175 and 1293
  • Level 2 protects against three shots of a 158-grain .357 magnum jacketed lead soft point at an FPS between 1250 and 1375
  • Level 3 protects against three shots of a 240-grain 44 Magnum Lead Semi-Wadcutter Gas Checked at an FPS between 1350 and 1485
  • Level 4 protects against one shot of a 180-grain .30 caliber rifle lead core soft point at an FPS between 2540 and 2794
  • Level 5 protects against one shot of a 150-grain 7.62mm rifle lead core full metal copper jacket military ball (.308 caliber) at an FPS between 2750 and 3025
  • Level 6 protects against five shots of a 124-grain 9mm full metal copper jacket with lead core at an FPS between 1400 and 1540
  • Level 7 protects against five shots of a 55-grain 5.56mm rifle full metal copper jacket with lead core (.223 caliber) at an FPS between 3080 and 3383
  • Level 8 protects against five shots of a 150-grain 7.62mm rifle lead core full metal copper jacket military ball (.308 caliber) at an FPS between 2750 and 3025 
  • Shotgun protects against three shots of a 12-gauge rifled lead slug at an FPS between 1585 and 1744 and three shots of a 12-gauge 00 buckshot (12 pellets) at an FPS between 1200 and 1320

Which UL Fire-Rated Windows Offer the Best Protection?

Three bullets embedded into a shattered UL rated bulletproof window

Aside from Levels 1 through 3, UL 752 testing standards are not linear. This means that one is not necessarily better than the other; they simply provide different types of protection.

For example, a product that is designated as Level 4 may protect better against that specific type of ballistic impact than one labeled as Level 5. A higher level does not necessarily mean that a product will hold up against all ballistics tested in the lower levels. 

However, UL 752 Levels 1, 2, and 3 generally provide lower levels of protection from handguns; these are often seen as crime deterrents at locations where cash is being handled and a handgun would most likely be used to rob the location.  Examples of these could be convenience stores, banks, pharmacies or check cashers. Levels 4 through 8 are often used to protect against larger ballistic threats like high-powered rifles and automatic weapons; these may be found at government and military facilities. 

What UL Fire-Rated Windows Are the Most Durable?

The type and amount of durability that UL-rated windows provide can depend on their makeup and use.

For example, products labeled as UL 752 Levels 1, 2, and 3 are often made of synthetic materials like acrylic or polycarbonate, which can be durable when used indoors. However, higher levels of protection like Levels 4 through 8 often include actual glass; these may be made with laminated glass or glass-clad polycarbonate.

Glass generally holds up better than acrylic and polycarbonate against weathering and general wear and tear, so look for these materials for exterior applications. 

How Long Do UL Fire-Rated Windows Last?

The lifespan of bullet-resistant glass depends on the material, the environment it’s being used in, and the care of the product.

For example, those used in exterior applications may need to be replaced more frequently than those installed indoors due to weathering and UV exposure. But even with interior applications, it is important that the products are cleaned properly and maintained in accordance with the product’s cleaning and maintenance instructions.  In general, many UL-rated windows can last up to 20 years.

How Do UL Fire-Rated Windows Hold Up in Extreme Weather Conditions?

UL 752 rated windows are specifically tested against ballistic impact in both hot and cold environments so you can be sure they will perform even in extreme weather. Also, the strong materials used in ballistic glass generally protect well against flying debris during major windstorms as well so there is an added safety level. Products that are specifically designated for outdoor use tend to hold up best in these conditions. 

If you’re looking for UL-rated windows to provide extra protection for your commercial or public building, contact Insulgard today.

We offer a huge range of products, from doors and windows to glazing and countertop systems. We also have a huge network of installers ready to put your new protective systems into use right away. Browse our BulletBlock line of products to find the most relevant options for your building or call our team to discuss your needs today. 

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