Security glass is a fortified glass or glass alternative which protects a property’s most vulnerable entryways and customer contact points. The panes can be strengthened to resist handheld weapons, projectiles, bullets and even explosions.
In addition to its defensive qualities, security glass is designed to break into non-lethal granules which won’t lacerate the skin. Some security glass will even remain trapped within its frame after it’s been broken.
Classifications & Standards of Security Glass
Commercial buildings in the U.S. require a certain standard of security glass in order to be compliant with state building codes. The organizations which provide these standards include:
- The American Society for Testing Materials (ASTM): This organization tests and standardizes security glass based on its ability to resist forced entry and explosions.
- The Underwriter’s Laboratory (UL): The Underwriter’s Laboratory classifies glass based on its resistance to firearms and types of bullets. For more information, see UL752, which rates bullet proof glass on a scale of 1 to 8.
- The European Standard (EN): The European Standard performs manual entry tests, classified under EN356. Tests measure how well a security glass can withstand axes, sledge hammers, torches and other attempts at forced entry.
Depending on your building type, you may need to look for glass that’s been inspected, tested and approved by one of the organizations above.
Types of Security Glass
Now that we know the organizations which grade security glass and the classifications those grades are based on, let’s look at the types of security glass out there on the market for a business.
Tempered or “toughened” glass is any glass that’s been thermally and chemically treated to increase its strength. In addition, the glass is able to “chunk” or crumble into small granular pieces rather than knife-like shards.
This vandalized telephone booth was outfitted with tempered glass. Like most tempered glass, it doesn’t hold up under sustained physical attack. But it’s less likely to cut if it breaks.
Uses: Vehicles, earthquake-prone areas
- Pros: Cheap, easy to install, stronger than standard float glass, mostly harmless if broken.
- Cons: Not a true security glass, as it can be broken fairly easy. Must be ordered to size, long delivery times.
Laminated glass is created by sandwiching a durable plastic interlayer (usually polyvinyl butyral, or PVB) between two panes of strengthened glass. The glass and PVB are chemically bonded to one another during the manufacturing process, making it incredibly difficult to break.
Laminated glass doubles as a safety glass. When the glazing it struck, it breaks within the frame, but is held in place by the PVB.
Another important aspect of laminated glass is that additional layers of glass and PVB can be added during the manufacturing process. Once laminated glass reaches a certain thickness (around 5 cm or more) it becomes bullet proof, meeting UL752 bullet proof standards up to level 8 (the highest possible).
In the image on the right for example, this bulletproof glass has taken three shots from a hand gun, and that still wasn’t enough to shatter the glass.
Uses: Aquariums, schools, banks, retail buildings, vehicles, earthquake-prone areas
- Pros: Limited bomb resistance, bullet resistance, very strong against manual forced entries and “smash-and-grab” theft.
- Cons: Expensive, strong but tends to crack easily.