Security Glass

Underwriters Laboratories standard UL 752 defines 8 levels of ballistic resistance, each tested against a specific weapon, round, and shot count. Level 1: 9mm handgun, 124 grain, 3 shots. Level 2: .357 Magnum, 158 grain, 3 shots. Level 3: .44 Magnum, 240 grain, 3 shots. Level 4: .30 caliber rifle, 180 grain, 1 shot. Level 5: 7.62mm NATO, 150 grain, 1 shot. Levels 6-7: 9mm submachine gun and 5.56mm rifle multiple shots. Level 8: 7.62mm NATO, 5 shots — the maximum residential and commercial specification.

The corresponding glass thicknesses are dramatic: Level 1 is 1-1/4" thick at about 8 pounds per square foot. Level 3 is 1-7/16" thick at 11 pounds per square foot. Level 8 is 2-3/4" thick at 27 pounds per square foot. That weight drives the frame system, the wall structure, and the install logistics. A Level 8 IGU in a 4x6 opening weighs about 650 pounds — boom-lift territory.

Most commercial installations top out at Level 3. Banks and credit unions historically spec Level 1 or 2 at teller lines (handgun threat). Jewelry stores spec Level 3. Government buildings and federal courthouses spec Level 4 or higher. We've installed Levels 1-4 across NJ; Level 5+ work is rare and almost always part of a federal facility scope.

Forced-entry resistance is governed by ASTM F1233 and UL 972. The threat model is different: instead of a single ballistic round, the attacker uses tools — sledgehammer, ax, pry bar — repeatedly over time. The glass has to survive sustained mechanical attack long enough for police response (typically 5-15 minutes).

ASTM F1233 has multiple classes based on attack tool. Class 1 covers hand-tool attack (hammers, screwdrivers). Class 3 covers power tools (sawzalls, grinders). Class 5 covers heavy demolition (sledges, fire axes). Most school and house-of-worship security spec lands at Class 1 or 2 — sufficient delay for first responders without the cost of full Class 5.

The practical fabrication for forced-entry glass is laminated with thick PVB or SentryGlas interlayers — typically 9/16" to 1" total thickness. The interlayer doesn't stop the attack on its own; it holds the broken glass together so the opening can't be cleared. An attacker with a sledge can break the glass in 30 seconds, but can't get through the opening because the laminate stays in place and they'd have to cut through it tooth by tooth.

We've been installing forced-entry glass at NJ houses of worship since 2019. The typical scope is a Class 1 laminated front-door package plus a Class 2 vestibule and sometimes a ballistic-rated rear window at the rabbi's, imam's, or pastor's office. The threat-vs-cost calculus is real — full ballistic protection across an entire building runs $200-400/sq ft installed and 99% of attacks are handled by Class 1 forced-entry plus access control.

NJ schools have been retrofitting security glass since the post-2018 wave of state grants. The Department of Homeland Security's SAFE Schools program and NJ's Securing Communities Against Hate Crimes grants have funded vestibule replacement at hundreds of districts. The typical school spec is a forced-entry-resistant laminated package at the main entry vestibule plus reinforced frame anchoring to the surrounding masonry.

We don't do ballistic glass at most schools — the threat model doesn't justify it and the cost would consume the entire grant on one opening. We do forced-entry-rated laminated (Class 1 or 2 per ASTM F1233) plus reinforced frame systems with longer fasteners into the rough opening framing. The combination buys 10-15 minutes of delay against an attacker with hand tools, which is the realistic response window for school resource officers and police.

Frame work matters as much as glass on school installs. Standard aluminum storefront frames pull out at the first sustained attack — the glass is fine but the frame fails. We upgrade to high-security frame systems from Total Security Solutions, Insulgard, or BR-Glass with stainless steel fasteners on 8" centers and structural anchoring into the wall, not the rough opening trim.

Since the Tree of Life attack in 2018 and the rise in attacks at Jewish, Christian, and Muslim institutions across the U.S., houses of worship have been upgrading security glass in significant numbers. NJ has funded a portion of this work through the Nonprofit Security Grant Program (NSGP), which provides up to $200,000 per institution for hardening including security glass.

The typical spec is a layered approach: forced-entry-resistant laminated at the main entry doors, ballistic Level 1 or 2 at any office or assembly area with a known target, and security film on existing windows that aren't being replaced. We've worked with synagogues in Bergen, Essex, and Monmouth counties; churches in Burlington, Camden, and Atlantic; and mosques in Passaic, Hudson, and Middlesex.

Concealability matters in religious settings. Many congregations don't want the visible signaling that comes with obvious ballistic glass — the thick edge, the visible inner layers. We work with manufacturers (Total Security Solutions, Armortex, Insulgard) on concealed installations where the security glass is sized and detailed to look like standard glazing from the congregation side.

Security glass is only as good as its frame. A UL 752 Level 3 IGU in a standard aluminum storefront frame fails at the frame anchor — not the glass. We use high-security frame systems for any ballistic install (Total Security Solutions Series 6500, Insulgard StrongStop, Armortex SR series) with structural anchoring through the frame head and jamb into solid backing.

Glazing details matter. Security glass requires deeper glazing pockets than standard glass — typically 7/8" to 1-1/4" deep — to prevent the glass from being pried out of the frame. The exterior glazing gasket has to be locked in, not a friction-fit gasket that can be pulled out from the outside.

Anchoring is the unsung hero. We don't anchor security glass frames into rough opening trim or shims — we anchor into solid backing, typically 1/4" steel plate behind the rough opening or expansion anchors directly into masonry/concrete. Stainless steel hardware throughout to avoid corrosion failure of the security system itself.