Product Spotlight: ST-STEEL

BIG DOOR
Apr 6
2 min read

Updated: Apr 30

The visual authority of iron frames, reborn in aluminum. For projects where the salt air wins every argument.

osoares ST-Steel window and door system installed in stone facade residence showing slim steel-look aluminum frames with glass panels — Source: Sosoares

Steel's aesthetic has defined coastal architecture for a century. The problem is, the coast destroys steel. ST-Steel closes that gap.

THE CASE FOR ST-STEEL

There is a particular tension in coastal design: the materials that read most powerfully against a seascape are frequently the ones least suited to survive it. Iron and steel frames carry an industrial elegance architects have leveraged for decades — slim sightlines, bold shadow lines, visual weight that glass alone cannot provide. Within half a mile of salt water, that language begins to corrode. Literally.

Sosoares developed ST-Steel as a direct answer to this constraint — an aluminum system engineered to recreate the proportions, sight lines, and frame geometry of traditional iron frames, without conceding ground on corrosion resistance, thermal performance, or longevity.

The system's 78mm (3') fixed frame and 85mm (3⅜") mobile frame were dimensioned to mirror the visual mass of steel, not minimize it. Polyamide thermal breaks at both depths bring the profile to modern envelope standards while preserving the structural depth that defines the look. Wind resistance rated to Class E1350. This is not an aesthetic exercise. It is a specified system that happens to look like something far older.

Sosoares ST-Steel system specifications including fixed frame 78mm, mobile frame 85mm, polyamide thermal break, and CE certification ratings

Three reasons this system earns its place on a coastal specification:

CORROSION IMMUNITY

Aluminum at the envelope means no rusting, no spalling, no maintenance cycle that steel demands within half a mile of saltwater. The aesthetic is preserved because the substrate is not degrading beneath it.

THERMAL CONTINUITY

Polyamide thermal breaks at both frame depths interrupt the cold bridge that made steel-look profiles a liability in high-performance envelopes. With appropriate glazing, U-values reach .23.

ACOUSTIC CONTROL

Tested to Rw 45 dB with acoustic laminated glazing, the system addresses the second major coastal challenge: wind and surf noise. The profile depth that gives ST-Steel its visual mass also contributes to sound attenuation.

Sosoares ST-Steel performance specifications showing 0.23 u-value thermal transmittance, 45db acoustic rating, E1350 wind resistance, and 2-1/8 inch max glazing depth

The Thermal Break in Action

Isothermal analysis — warm interior (orange) to cold exterior (blue). The polyamide thermal break visibly interrupts heat transfer at the frame junction, eliminating the cold bridge that disqualifies most steel-look systems from high-performance envelopes.

sothermal analysis diagram of Sosoares ST-Steel polyamide thermal break showing heat transfer interruption at frame junction from warm interior orange to cold exterior blue — Source: Sosoares

The T-Bar Difference

Unlike the flat bar or beveled trim used by most manufacturers, ST-Steel's true T-shaped profile replicates the authentic shadow line and visual weight of traditional iron frames.