Eight commercial glass categories compared by thickness, strength, safety classification, thermal performance, and applicable codes. From standard tempered storefronts to bullet-resistant security glazing and fire-rated assemblies, this guide covers the specifications that architects, contractors, and building owners need.
Last Updated: March 2026
Comprehensive comparison table covering all major commercial glass categories with specifications, safety classifications, and applicable code references.
| Glass Type | Thickness | Strength | Safety Class |
|---|---|---|---|
| Tempered | 6-12mm | 4-5x annealed | CPSC Cat I/II |
| Laminated | 6.4-25mm+ | 1-2x (holds on break) | CPSC Cat I/II |
| Insulated (IGU) | 20-32mm | Varies by panes | Varies by panes |
| Spandrel | 6-8mm HS/tempered | 2-5x annealed | Non-vision opaque |
| Fire-Rated (Ceramic) | 5-7mm | 2-3x annealed | Fire-protective |
| Fire-Rated (Intumescent) | 16-50mm | Laminated | Fire-resistive |
| Security (Bullet-Resistant) | 21-55mm+ | Multi-ply laminated | UL 752 rated |
| Decorative (Textured/Fritted) | 6-12mm | As base glass | As base glass |
The workhorse of commercial glazing. Standard 6mm tempered glass in aluminum storefront framing is the baseline specification for retail storefronts, office entries, and commercial windows. Tempered glass meets CPSC 16 CFR 1201 Category I and II safety glazing requirements. Wind load capacity per ASTM E1300 depends on panel size, support conditions, and glass thickness -- a 6mm tempered panel in a 4-sided frame can resist approximately 50-70 psf wind pressure for typical storefront panel sizes. For larger panels or higher wind zones, 8mm or 10mm tempered glass is specified.
Required for all overhead glazing (skylights, canopies, sloped glazing) in commercial buildings because laminated glass holds together when broken, preventing glass fragments from falling on occupants below. In security applications, laminated glass resists forced entry because the interlayer maintains the barrier even after the glass breaks. Hurricane-zone laminated glass (ASTM E1996, Miami-Dade TAS 201/202/203) must withstand large and small missile impact testing. For overhead applications, heat-strengthened laminated glass is preferred over tempered laminated because heat-strengthened breaks into larger pieces that better adhere to the interlayer.
Spandrel glass creates the visual continuity of an all-glass facade while concealing the building structure between floor levels. The opaque coating (typically ceramic frit) is applied to surface 4 (the interior face) and must be color-matched to the vision glass when viewed from the exterior. Behind the spandrel glass, insulation (typically 2-4 inches of mineral wool or rigid board) provides thermal performance and fire resistance. A shadow box construction uses a reflective back panel behind the insulation to add visual depth. Spandrel glass is always heat-strengthened or tempered because the opaque coating absorbs solar energy, raising the glass temperature 20-40 degrees F above ambient.
Commercial fire-rated glass has evolved significantly from traditional wired glass. Modern ceramic glass products (such as Pyran and FireLite) provide 20-180 minute fire protection in a clear, safety-rated product that is 6x stronger than wired glass. For fire-resistive applications (where radiant heat must also be blocked), multi-layer intumescent glass products intumescent (turn opaque and foam) when exposed to fire, creating an insulating barrier. Fire-rated glass must be installed in rated frames and tested as a complete assembly. The fire rating of the glass must match or exceed the fire rating of the wall it is installed in.
UL 752 defines eight levels of bullet-resistant glazing based on the weapon, ammunition, and number of shots the glass must stop without penetration.
| Level | Weapon | Ammunition | Shots | Min. Thickness |
|---|---|---|---|---|
| Level 1 | 9mm Handgun | 124gr FMJ | 3 | ~21mm |
| Level 2 | .357 Magnum | 158gr JSP | 3 | ~25mm |
| Level 3 | .44 Magnum | 240gr SWC | 3 | ~32mm |
| Level 4 | .30-06 Rifle | 180gr SP | 1 | ~35mm |
| Level 5 | 7.62mm Rifle | 150gr M2 AP | 1 | ~42mm |
| Level 8 | 7.62mm Rifle | 166gr AP | 5 | ~55mm+ |
Commercial storefronts typically use 6mm (1/4 inch) tempered glass in single-pane applications or insulated glass units (IGUs) with tempered panes for energy-efficient facades. The glass is installed in aluminum storefront framing systems (commonly 2-1/2 inch or 4-1/2 inch depth). For ground-floor retail with security concerns, laminated tempered glass provides both impact resistance and forced-entry protection. High-traffic locations and government buildings may require security laminated glass rated to UL 972 or ASTM F1233. All commercial storefront glass at or near ground level must be safety glazed per IBC Chapter 24.
Spandrel glass is opaque glass used in curtain wall and facade systems to conceal structural elements between vision areas. It is typically made by applying a ceramic frit (opaque paint) to the back surface of heat-strengthened or tempered glass, then firing it at high temperature to permanently bond the coating. Spandrel glass hides floor slabs, columns, mechanical equipment, insulation, and fire-stopping materials. It is color-matched to the vision glass to create a uniform facade appearance. Spandrel panels must be heat-strengthened or tempered because the opaque coating absorbs solar heat, creating thermal stress that can break annealed glass.
Commercial fire-rated glass is available in ratings from 20 minutes to 3 hours, depending on the product type. Wired glass (legacy): 45-minute rating in steel frames. Ceramic glass (Pyran, FireLite): 20 to 180 minutes, available as fire-protective or fire-resistive. Intumescent laminated glass: up to 120 minutes, provides both fire and impact safety. Fire-resistive glass (such as SuperLite II-XL) blocks both flames and radiant heat transfer, meeting the strictest fire codes (ASTM E119 / UL 263). Fire-protective glass blocks flames and smoke but may allow radiant heat transfer. The required rating depends on the wall assembly type and building code requirements.
Fire-protective glass prevents the passage of flames and smoke through an opening for the rated duration. However, it may allow radiant heat to transfer through the glass, which can ignite materials on the non-fire side. Fire-resistive glass blocks both flames and radiant heat transfer (meeting hose-stream and temperature-rise requirements of ASTM E119). Fire-resistive glass is required in 1-hour and 2-hour fire barriers, exit enclosures, and exit passageways where limiting radiant heat is critical for occupant safety. Fire-protective glass is acceptable in 1-hour fire partitions, corridor walls, and some exterior wall applications where radiant heat transfer is less critical.
Commercial security glass uses multi-ply laminated constructions designed to resist specific threat levels. Forced entry resistance (UL 972): typically 7.5mm to 12mm laminated glass that resists break-through from hand tools for 1-5 minutes. Bullet-resistant glass (UL 752): ranges from Level 1 (9mm handgun, 3 shots -- 21mm total thickness) to Level 8 (7.62mm rifle, 5 shots -- 55mm+ total thickness). Blast-resistant glass (ASTM F1642, GSA-TS01): laminated glass in specialized frames designed to contain glass fragments during explosive events. All security glass must be tested to the applicable standard and installed in rated frame systems.
Vision glass is the transparent portion of a facade that allows occupants to see through and admits daylight. It is typically an insulated glass unit (IGU) with Low-E coatings and gas fill for energy performance. Spandrel glass is the opaque portion that conceals structural elements, floor edges, and mechanical systems. Spandrel glass uses ceramic frit, opaque paint, or shadow box construction to prevent see-through while maintaining the exterior appearance of a continuous glass facade. Both glass types should be color-matched to create a uniform exterior. Vision glass is the energy-critical component, while spandrel glass is primarily aesthetic and concealment.
Commercial building glass is governed by the International Building Code (IBC), Chapter 24 (Glass and Glazing), along with referenced standards. Key standards include: ANSI Z97.1 and CPSC 16 CFR 1201 for safety glazing identification and performance. ASTM E1300 for determining wind-load resistance of glass panels. ASTM C1036 for flat glass specification and classification. ASTM E2190 for insulating glass unit performance. NFRC 100/200/400 for thermal performance ratings. ASCE 7 for structural wind and seismic load determination. IBC Section 2406 specifies where safety glazing is required in commercial buildings, including hazardous locations, doors, sidelights, and glass near walking surfaces.
Our commercial glass specialists work with architects, contractors, and building owners throughout the DMV area. From storefront glazing to fire-rated assemblies and security glass, we provide expert specification assistance and installation. Backed by our Comprehensive Warranty.
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