Bullet-resistant glass is a multi-layer glazing assembly, ¾ inch to 4 inches thick, engineered to absorb and distribute the energy of a firearm projectile and prevent penetration. It is rated under UL 752, Standard for Bullet-Resisting Equipment, 11th Edition, across Levels 1 through 10. Armortex manufactures UL 752 11th Edition glazing in laminated polycarbonate, glass-clad polycarbonate, and acrylic compositions, listed across Levels 1 through 10. The accurate industry term is bullet-resistant, not bulletproof.
Key Facts
| Product Type | Bullet-resistant glazing: laminated glass, glass-clad polycarbonate, laminated polycarbonate, acrylic |
| Primary Standard | UL 752, Standard for Bullet-Resisting Equipment, 11th Edition |
| Typical Thickness | ¾ inch to 4 inches, increasing with protection level |
| Protection Range | UL 752 Levels 1–10 |
| Spall Designation | UL 752 classifies glazing as no spall, low spall, or unclassified; Armortex TP-series laminated polycarbonate carries a no-spall designation |
| CSI Section | 13 10 00 Bullet Resistant Products |
| Common Applications | Transaction windows, entry vestibules, reception counters, control rooms |
Key Takeaways
- UL 752 Level 1 tests three shots of 9mm full metal copper jacket at 124 grains, the baseline threat for commercial and retail environments.
- Glass-clad polycarbonate spans UL 752 Levels 1 through 10, the widest protection range of any glazing composition available to specifiers.
- Spall is a separate UL 752 designation from protection level. Glazing is classified no spall, low spall, or unclassified, and no spall is specified wherever personnel work close to the protected face.
- Composition, not level alone, drives thickness and weight. Armortex publishes UL 752 Level 1 laminated polycarbonate (TP 100) at 0.77 inch and 4.8 pounds per square foot, and UL 752 Level 1 acrylic (TA 100) at 1.25 inches and 7.6 pounds per square foot.
- Rated glazing installed in an unrated frame is not a compliant assembly, because UL 752 rates the complete system rather than the lite alone.
What Is Bullet-Resistant Glass?
Bullet-resistant glass is a laminated composite, not a single material. Alternating rigid and flexible layers are stacked in sequence and fused in an autoclave, where heat and pressure consolidate every ply into a single optical unit without voids or delamination. Monolithic acrylic is the exception: it is produced as one cast sheet rather than a bonded stack.
Each layer has a defined role. Outer glass provides hardness that deforms and fragments the incoming projectile. PVB (polyvinyl butyral) interlayers bond the plies and absorb shock. EVA (ethylene-vinyl acetate) interlayers are specified where moisture resistance and long-term optical clarity matter. A polycarbonate or acrylic backing captures residual energy and contains fragments.
Specifiers encounter the product under many names: ballistic glazing, ballistic-grade glass, BR-rated window, UL 752 window, and security glazing. All describe glazing rated to a defined standard through independent testing.
The persistent misconception is that thicker is always better. Protection must match the assessed threat; specifying above it adds cost and weight with no corresponding safety benefit. A second misconception is that ballistic film is a substitute. Film runs 3 to 8 mils against ¾ inch to 4 inches for rated glazing; it can reduce spall and delay forced entry, but it does not carry a UL 752 level and does not stop projectiles.
Bullet-Resistant Glass Types Compared
| Type | Best For | Key Limitation | Relative Cost |
| All-glass laminate | Exterior openings requiring optical clarity and weather performance | Heaviest composition; UL 752 Levels 1–8 | Mid-to-high |
| Glass-clad polycarbonate | Interior and exterior openings at any level, UL 752 Levels 1–10 | Labor-intensive fabrication | Mid-to-high |
| Laminated polycarbonate | Interior counters where weight governs, UL 752 Levels 1–3 | Requires abrasion-resistant coating | Lower |
| Monolithic acrylic | Interior barriers at UL 752 Level 1–2 handgun threats | No interlayer structure; not viable against rifle rounds | Lowest |
Where Bullet-Resistant Glass Is Used
Bank teller lines and pharmacy counters. Transaction windows at UL 752 Level 1 address the 9mm threat characteristic of high-cash retail environments.
Courthouse clerk windows and police station reception. Levels 1 through 3 apply where elevated handgun threats are assessed, frequently paired with deal trays and speak-through systems.
Embassy glazing and critical infrastructure control rooms. UL 752 Level 5 addresses the 7.62×51mm NATO cartridge where military-grade rifle threats enter the design basis.
Hospital emergency departments and behavioral health units. Levels 1 and 2 protect nurse stations and dispensary windows while preserving the sightlines clinical staff need.
Correctional visitation and guard stations. Level 3 addresses the .44 Magnum handgun threat at visitation and control openings. Where 12-gauge shotguns are standard facility equipment, the applicable criteria are the separate UL 752 shotgun designations, not Levels 9 and 10, which cover armor-piercing rifle and .50 caliber threats.
Applicable Codes and Standards
| Standard | What It Governs | Why It Matters |
| UL 752, 11th Edition | Ballistic performance of glazing and assemblies, Levels 1–10 | UL Listed status confirms independent testing, not self-certification |
| ASTM F1233 | Security glazing under ballistic and forced-entry attack | Establishes classes for delay time, which UL 752 does not measure |
| EN 1063 | European security glazing, classes BR1–BR7 | Governs projects specified to European criteria |
| GANA Glazing Manual | Glazing installation practice | Field practice determines whether the tested rating survives installation |
| ISO 9001 | Manufacturer quality management systems | Audited process control matters where production variance affects life safety |
Edition note: UL Solutions has issued a 12th edition of UL 752, which clarifies how bullet-resisting assemblies such as gun ports, deal trays, and package passers are tested and evaluated. The 11th edition remains the basis for the Performance Level 1–10 designations in general architectural use. Confirm which edition the project specification and the manufacturer’s listing each cite, because they are not always the same.
Cost and Lifespan
Glazing cost is driven by protection level, composition, and opening configuration. Thickness — and with it, material cost — rises significantly at the transition from handgun Levels 1 through 3 to rifle Levels 4 through 8. Monolithic acrylic is the lowest-cost composition; glass-clad polycarbonate and all-glass laminates occupy the mid-to-high range. Custom sizing and transaction hardware add to cost and lead time. No published average price is cited here, because rated glazing is quoted per opening against a specific level, composition, and frame.
Service life is governed by composition and exposure rather than any published interval. All-glass laminates and glass-clad polycarbonate are long-lifespan products, and outer glass layers extend exterior service life through superior scratch and weather resistance. Uncoated polycarbonate degrades faster under UV and abrasion. Maintenance is routine cleaning.
Limitations and When Not to Use It
Where forced-entry delay is the primary objective. UL 752 measures projectile penetration, not resistance to sustained tool attack. Glazing tested to ASTM F1233 addresses combined threats directly, and UL 972 addresses burglary-resisting glazing.
Where the opening faces low ballistic risk. Security window film reinforces existing glass against vandalism and smash-and-grab at a fraction of the cost, without frame replacement. It is not rated glazing and cannot be specified to a UL 752 level.
Where the wall itself is the exposure. Glazing protects the opening only; ballistic fiberglass composite panels address the surrounding drywall assemblies.
Where structural capacity is limited. Bullet-resistant glazing is substantially heavier than standard glazing, and framing, sill details, and anchorage must be evaluated before the level is fixed.
How to Specify Bullet-Resistant Glass
- Specify glazing and frame as one rated assembly under CSI Section 13 10 00, never as separate line items.
- Require the UL file number and UL Listed documentation rather than a manufacturer compliance statement.
- State the required UL 752 level and edition, and cite the security assessment establishing it.
- Add the no spall or low spall UL designation wherever the protected face adjoins occupied space.
- Identify frame material — aluminum, hollow metal, or stainless steel — and any transaction hardware in the same section.
- Armortex publishes BIM objects and technical submittals covering glazing, frames, doors, and transaction accessories, which allows the assembly to be coordinated and submitted from a single manufacturer rather than assembled from separately rated components.
Two errors recur. The first is omitting the frame rating, which voids the assembly rating regardless of the glazing specified. The second is specifying polycarbonate for an exterior opening without an abrasion-resistant coating, which produces hazing and premature replacement.
Frequently Asked Questions
Is bullet-resistant glass actually glass?
Not always. The category includes all-glass laminates, glass-clad polycarbonate, laminated polycarbonate, and monolithic acrylic. Only the first two contain glass. All are rated under UL 752, and the composition is selected based on threat level, weight limits, and whether the opening is interior or exterior.
How thick is bullet-resistant glass?
Rated glazing runs ¾ inch to 4 inches thick, increasing with protection level. Handgun-rated assemblies at Levels 1 through 3 sit at the lower end — published laminated polycarbonate make-ups start below one inch — while rifle-rated glazing at Levels 5 through 8 often exceeds two inches of total depth to defeat higher-velocity rounds.
Can bullet-resistant glass be made into a transaction window?
Yes. Transaction configurations integrate deal trays, transaction drawers, package receivers, speak-through systems, and gun ports into the rated assembly. Frame options include aluminum, hollow metal, and stainless steel in fixed, sliding, hinged, baffle, and clamp-on configurations.
Does bullet-resistant glass look different from ordinary glass?
Modern assemblies preserve high optical clarity. Glass-clad polycarbonate delivers excellent clarity because the outer glass carries the exposed surface. Monolithic cell-cast acrylic often rivals standard float glass optically, since it is produced as a single uniform sheet rather than a bonded stack.
Which UL 752 level stops an AR-15 round?
Level 7 addresses the 5.56×45mm round used in AR-15 pattern rifles, tested at five shots. Level 8 covers five shots of 7.62×51mm rifle fire and is the highest level commonly specified for architectural applications. Levels 9 and 10 move to armor-piercing .30 caliber and .50 caliber threats and are largely military and federal in scope.
Can existing windows be upgraded to bullet-resistant glazing?
Yes, within limits. Aluminum clamp-on frame systems install over an existing opening without full frame replacement, and hollow metal split frames serve openings where clamp-on is unsuitable. The surrounding structure must be evaluated for the added weight before the level is fixed.
Sources
- Underwriters Laboratories, UL 752, Standard for Bullet-Resisting Equipment, 11th Edition.
- UL Solutions, “What Does It Take to Stop a Speeding Bullet?” — UL 752 edition and shotgun designation guidance. ul.com/news/what-does-it-take-stop-speeding-bullet
- ASTM International, ASTM F1233, Security Glazing Materials and Systems.
- CEN, EN 1063, Glass in Building — Security Glazing.
- Glass Association of North America, GANA Glazing Manual.
- International Organization for Standardization, ISO 9001, Quality Management Systems.
- S. General Services Administration, Physical Security Design Criteria.
- National Institute of Justice, NIJ Standard 0108.01, Ballistic Resistant Protective Materials.
- Armortex, “What UL 752 Means When Specifying Bullet-Resistant Glazing,” published product data for TP 100, TP 200, TP 300, and TA 100 glazing, updated July 2026. armortex.com/ul-752-specifying-bullet-resistant-glazing
Related: Ballistic vs. Impact Resistance · Laminated Ballistic Glass vs. Polycarbonate vs. Glass-Clad Polycarbonate · Security Window Film vs. UL 752 Ballistic Glazing
Last updated: August 2026