Quick answer: Aluminum storefront systems are identified by series number that indicates face dimension (the visible width of the mullion) and depth. The most-installed systems on Florida commercial projects are Series 451T (1-3/4" face, thermally broken), 501T (2" face, thermally broken), 601T (2-1/4" face, thermally broken), and 701T (2-1/2" face, thermally broken). Each has different wind ratings, glass thicknesses, and price points.
The first digit indicates face dimension category. The 'T' suffix indicates a thermal break (a polyamide isolator between the interior and exterior aluminum that improves U-factor). Series 451T has 1-3/4" face. Series 501T has 2" face. Series 601T has 2-1/4" face. Series 701T has 2-1/2" face. Deeper systems = higher wind ratings and larger spans.
1-3/4" face, 4-1/2" depth. Standard for ground-floor retail, restaurant, and office TI. Single-glazed (1/4" tempered) up to 12 feet tall. Max wind pressure roughly 35-50 PSF depending on glass and span. Cheapest in the family. Best for inland Florida, non-HVHZ work, and small storefront jobs.
2" face, 4-1/2" depth. Same depth as 451T but wider face. Accepts insulated glass (1" IG) and laminated impact glass. Standard for HVHZ retail and restaurant work. Max height around 14 feet. Typical price premium over 451T: 15-25%.
2-1/4" face, 5" depth. Standard for hotel ground floor, larger restaurant fronts, and medical office buildings. Accepts 1" IG and impact glass. Max height around 16 feet. Typical price premium over 501T: 10-15%.
2-1/2" face, 6" depth. For high-wind exposures (HVHZ Zone 4), tall storefronts (16-20 feet), and storefront-to-curtain-wall transition zones. Accepts thick laminated IG. Typical price premium over 601T: 12-20%.
Calculate design wind pressure first. Match the system's tested DP rating to your project's calculated DP, with a 20% safety margin. Then size for opening height. Then optimize for cost. Never spec a system that's under-rated for your wind load — it won't pass permit.
Series 451T has a 1-3/4" face dimension and a 4-1/2" depth, designed for single-glazed assemblies. Series 501T has a 2" face and accepts insulated and impact glass. 501T is the upgrade typically required for HVHZ work.
For HVHZ-rated storefront, Series 501T, 601T, or 701T (or equivalent thermally-broken systems from other manufacturers) are most common. The specific series depends on wind load and opening height.
The 'T' indicates a thermal break — a polyamide isolator inside the aluminum extrusion that reduces heat transfer. Thermal-break systems are required by FBC Energy Conservation chapter on most commercial buildings.
Yes, but each section must independently meet wind load requirements. It's most common to use a heavier-duty system on corner zones (higher wind pressure) and a standard system on field walls.
Multiple manufacturers produce equivalent systems: Kawneer, YKK AP, Tubelite, US Aluminum, and EFCO are the major brands. Profiles, ratings, and NOAs differ slightly between manufacturers.
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