There are many reasons why homeowners are looking to upgrade their windows and make them more secure. Some of the ways that bulletproof windows can help protect and secure your home include:
- Add protection from toys, stray golf balls, or landscaping accidents
- Add protection during storms and weather incidents
- Reduce UV damage to interior décor
- Add protection from crime or vandalism
Bulletproof glass can be coated to resist UV rays, or tinted to reduce visibility into the home, and can protect your home and your belongings from a wide range of incidents and accidents. They aren’t just for bullets.
Bulletproof Ratings and What They Mean
Underwriter’s Laboratory (UL) has done extensive testing and has developed a rating system for bulletproof glass. In brief, the first five UL ratings break down like this:
- UL bulletproof rating 1: Will stop 3 9mm bullets
- UL bulletproof rating 2: Will stop 3 .357 Magnum bullets
- UL bulletproof rating 3: Will stop 3 .44 Magnum bullets
- UL bulletproof rating 4: Will stop 1 30-06 bullet
- UL bulletproof rating 5: Will stop 1 7.62mm bullet
Most consumer-grade bulletproof materials do not exceed UL rating 4, but any product claiming to be bulletproof should have the appropriate UL rating.
Secure Window Materials
Some of the most common materials used in bulletproof windows are:
A security film is an aftermarket product that can be applied to existing windows. They are thin sheets of polyester or PET with an adhesive that sticks them to regular window glass. Glass treated with these kinds of films holds the window together in one piece if it is broken or shattered, making it behave like a laminated glass window.
These films are of various thicknesses, with thicker sheets providing more protection, and have various degrees of optical clarity. They can have UV protective properties, be tinted, or have decorative patterns.
Advantages of using security film to protect a window
- Can be installed on existing windows, making installation simpler and more affordable
- Toughen glass to resist shattering in earthquakes, weather events, or during an intrusion
- Can add aesthetically to the home with tinting, patterning, or UV protection
Disadvantages of security film
Even the most advanced security film is not bulletproof when used on standard residential glass
Security film can offer GSA protection up to 2, which is a measure of blast resistance, but no current security film has a UL rating. They can delay unwanted entrance into a building, and provide affordable protection from shattering, but are not bulletproof.
Laminated glass has a thin layer of PVB and/or EVA between two sheets of glass, which results in shatterproof glass. Most people are familiar with laminated glass because it is used in car windows and windshields, and also in the windows of skyscrapers and tall buildings where falling broken glass presents a hazard. Laminated glass bonded with EVA is also a very effective sound insulator and UV blocker.
As with all bulletproof materials, laminated glass is available in various thicknesses, and the thicker it is, the more protection it offers. However, laminated glass can become very heavy when it is thick, and sometimes a layer of polycarbonate is added to preserve strength while reducing weight. Consumer-level laminated glass can offer bullet protection up to UL 3, but such sheets of laminated glass are more than 1.5 inches thick.
- Offers great protection from shattering
- Some laminated glass can be especially sound-resistant, reducing spying and eavesdropping
- Laminated glass is often naturally UV resistant
- Bulletproof laminated glass is very thick and heavy for residential use
Laminated glass was the first bulletproof glass, and has largely been replaced by more modern materials that are lighter in weight and easier to work with. However, there are still many excellent applications for laminated glass, and it does have some special properties.
Acrylic is frequently used in bulletproof and bullet resistant windows. Better known as plexiglass, acrylic glass is a synthetic polymer that weighs half as much as glass, and effectively diffuses impact. Acrylic glass is tough, but stable enough to be cut and drilled, making it a popular choice for many bullet resistant applications. At thicknesses of slightly over 1.25 inches, it can typically achieve a UL rating of 2.
- Acrylic is resistant to UV rays and water damage, so it does not yellow or turn brittle over time, giving it great durability
- Easy to cut, work with, and install
- Excellent visual clarity
- Lighter weight than glass
- Acrylic glass needs to be much thicker than a standard home window in order to be bulletproof
Acrylic is easy to get, work with, and install, and provides excellent shatter resistance and great durability. It maintains optical clarity, can be made scratch-resistant, and is light weight. While acrylic glass that is thin enough for most home windows isn’t bulletproof, it’s still a great option for home security.
Polycarbonates are thermoplastic polymers that are strong, tough, and optically clear. It is a third the weight of acrylic, and the layers of polycarbonate are soft and flexible. They absorb and diffuse the energy from impacts, rather than resisting them.
Most people encounter polycarbonate in “theft-proof” product packaging that is impossible to open by hand, safety glasses, and windscreens in smaller vehicles like motorcycles. Polycarbonate that is 1.25 inches thick can typically achieve a UL rating of 3, and just ¾ of an inch is needed for a UL rating of 1.
- Light weight and easy to work with
- Extremely tough and strong for the weight
- Will degrade over time without UV protection
- Will scratch, tint, or show wear over time
Polycarbonate is a great choice for bulletproof glass because it is so light, thin, and easy to work with. However, it is not a very durable material, and the likelihood that it will tint and degrade in UV light, and show scratches and wear over time don’t make it the ideal choice for a home.
Glass-clad polycarbonate is a multi-layered material, often known as “ballistic glass.” Typically the exterior or threat side of the material is made of a layer of glass, because glass resists wear and scratching.
The interior side is made of polycarbonate, and in between are layers of PVB and/or TPU. Glass-clad polycarbonate is, clearly, slightly thicker than polycarbonate alone, but the addition of the glass layer helps to add more durability. Glass-clad polycarbonate is the highest grade of bullet-resistant glass, and can go up to a UL rating of 8.
- Excellent bullet resistance
- More durable than polycarbonate alone
- Poor light transmission
- Difficult to fabricate and work with
Glass-clad polycarbonate is the window material with the most bullet-stopping material, and with the addition of glass to help improve aesthetics and durability. It is also expensive, due to the difficulty of making it and the difficulty of working with it.
If you want bulletproof windows in your home, there are a lot of options in different materials at different price ranges for different threat levels. As our technology improves, we can expect even more improvements in bulletproof glass over time.