Quick answer: Commercial glass comes in five base types: annealed (float), tempered, heat-strengthened, laminated, and insulated. Each has specific uses, performance characteristics, and Florida code applications. Most commercial buildings use combinations — e.g., insulated laminated impact-rated tempered (4 of the 5 types in one assembly).
All commercial glass starts as annealed float glass. Manufactured on a bath of molten tin to produce a flat, polished sheet. Annealed glass is not safety glass and breaks into sharp shards. Used directly in non-hazardous locations (above 60" from floor, away from doors). Cost basis for all other types.
Tempered glass is heat-treated to 1,200°F and rapidly cooled. The result: 4-5x stronger than annealed, and a safe break pattern (small granular pieces). Required in 'hazardous locations' per FBC: doors, sidelights, glass within 24" of doors, glass within 18" of floor, shower/tub enclosures, stairs.
Heat-strengthened glass is heat-treated like tempered but cooled more slowly, resulting in 2x annealed strength (vs 4-5x for tempered). NOT safety glazing. Used in spandrel, curtain wall vision lites (often as outboard of laminated assemblies), and applications where higher strength than annealed is needed but the safety break pattern of tempered is not required.
Laminated glass is two layers of glass bonded to a tough plastic interlayer (PVB or SGP). When broken, the interlayer holds the assembly together. Required for HVHZ impact-rated openings (TAS 201/202/203), structural glass railings, overhead glazing, and security applications. The dominant safety/structural glass type on Florida commercial work.
Insulated glass units are two or more glass lites separated by a sealed cavity (typically 1/2" with argon or air). The sealed cavity reduces heat transfer. Required by FL Energy Code to meet U-factor ≤ 0.50 for most commercial vertical fenestration. Standard IGU: 1/4" outboard + 1/2" airspace + 1/4" inboard = 1" nominal thickness.
Typical Florida storefront IGU: 1/4" laminated impact (laminated outboard) + 1/2" air + 1/4" tempered inboard. This combines: laminated (HVHZ impact), tempered (safety break pattern), insulated (energy code), and low-E coating (energy code SHGC). Four glass types in one assembly.
Five base types: annealed (float) glass, tempered glass, heat-strengthened glass, laminated glass, and insulated glass units (IGU). Most commercial assemblies combine 2-3 of these types.
Tempered is heat-treated and rapidly cooled, achieving 4-5x annealed strength and a safe granular break. Heat-strengthened is treated more slowly, achieving 2x annealed strength but NOT a safety break pattern. Heat-strengthened is used in spandrel and curtain wall vision lites; tempered is used at safety-glazing locations.
Yes — HVHZ impact-rated assemblies require laminated glass (typically tempered laminated with PVB or SGP interlayer). The laminated structure maintains integrity after impact, which is what passes the TAS 201/202/203 testing.
Insulated glass units reduce heat transfer dramatically (U-factor 0.30-0.45 vs 1.10 for single pane). Required by Florida Energy Code for all conditioned commercial space.
Yes — a single lite can be heat-treated (tempered or heat-strengthened), laminated (with another lite via interlayer), and coated (low-E). A typical Florida HVHZ storefront IGU combines 4 attributes in one assembly: laminated + tempered + insulated + low-E coated.
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