Resource · Plain-English Guide

Thermal Break Aluminum Framing Explained

Quick answer: Thermal break aluminum framing uses a non-conductive polyamide isolator (typically 14-32mm wide) between the interior and exterior aluminum surfaces. This breaks the thermal bridge that otherwise allows heat to transfer directly through the metal, dramatically improving U-factor. Required by Florida Energy Code for most commercial fenestration in Climate Zones 1 and 2.

How thermal break works

Aluminum is a thermal conductor — heat transfers through it at 1,400 BTU·in/hr·ft²·°F. Without a break, the interior and exterior surfaces of an aluminum frame are at nearly the same temperature, defeating the purpose of insulated glass. The thermal break (polyamide) interrupts this conductivity, allowing the interior surface to stay closer to room temperature.

Thermal break widths and performance

Standard thermal break widths: 14mm, 18mm, 24mm, 32mm. Wider = better U-factor. Common Florida commercial frames use 24mm or 32mm thermal breaks. The wider thermal break also reduces condensation risk on the interior frame surface during cold weather.

FL Energy Code requirements

Florida Building Code Energy Conservation chapter (FBC EC) requires commercial vertical fenestration in Climate Zone 1 (South Florida) to meet U-factor ≤ 0.50. Climate Zone 2 (rest of FL) requires ≤ 0.55. Without thermal break, aluminum framing typically pushes total U-factor to 0.65-0.85 — fails code.

Common thermal-broken systems on Florida commercial

ESWindows ES-8000T, ES-CS1325 (T = thermal break). ESWindows YHS 50 TU, YHS 60 TU. ESWindows T14651. EFCO 433. All offer current FL Product Approvals and Miami-Dade NOAs.

Cost premium for thermal break

The premium is required by code for most commercial work, so it's not really an optional cost — it's the baseline.

Coordination with glass spec

Thermal-broken framing must pair with low-E insulated glass to achieve target U-factor. The framing alone is necessary but not sufficient. The complete assembly U-factor is calculated per NFRC 100 procedure.

Frequently asked

What is thermal break aluminum?

Thermal break aluminum framing uses a polyamide isolator between the interior and exterior aluminum surfaces. This breaks the thermal bridge that would otherwise allow heat to conduct directly through the metal, improving U-factor.

Is thermal break required by Florida code?

Yes — Florida Energy Code requires commercial vertical fenestration to meet U-factor ≤ 0.50 (Climate Zone 1) or ≤ 0.55 (Climate Zone 2). Achieving this without thermal break is nearly impossible.

Which manufacturers offer thermal-broken storefront?

ESWindows ES-8000T (, ES-CS1325), ESWindows (YHS 50 TU, YHS 60 TU), ESWindows (T14651), EFCO (433) all offer thermal-broken commercial storefront systems for Florida.