Resource · Plain-English Guide

Structural Silicone Glazing Explained

Quick answer: Structural silicone glazing (SSG) is a curtain wall or storefront technique where glass is bonded directly to the aluminum framing with high-performance structural silicone — eliminating the exterior aluminum cap and producing a flush, all-glass exterior appearance. SSG is used on Class-A office, luxury hotel, and architecturally-driven commercial projects.

What structural silicone actually does

In traditional curtain wall, glass is held to the framing by an exterior aluminum pressure plate or cap. The cap creates a visible aluminum grid on the building exterior. Structural silicone replaces the cap with high-strength silicone adhesive — the glass is bonded directly to the aluminum mullion. The result: a flush all-glass exterior with no visible aluminum cap, only the visible grid of where mullions are behind the glass.

Two- vs four-sided SSG

Two-sided SSG keeps aluminum caps on the horizontal joints and uses silicone on the vertical joints (or vice versa). Four-sided SSG uses silicone on all four edges of the glass lite. Four-sided is the higher-performance, more dramatic appearance — and the more expensive.

HVHZ and SSG: factory-bonded units required

Miami-Dade and HVHZ jurisdictions require structural silicone joints to be factory-bonded — the glass and aluminum sub-frame are bonded in a controlled fabrication environment, not on-site. The bonded assembly then ships to site and installs as a single panel. This is more expensive than stick-built SSG but ensures consistent silicone cure quality.

Cost premium for SSG

The premium covers: higher-grade silicone material (Dow 995 or equivalent), engineering certification of the bond, factory bonding labor for HVHZ work, and longer shop drawing timelines.

When SSG is the right call

Class-A office where the architect specified a flush all-glass exterior. Luxury hotel where finish matters. Award-targeting architectural projects (AIA awards, USGBC LEED Platinum). High-end mixed-use where ground-floor commercial wants a continuous glass look. Skip SSG on basic commercial, retail TI, restaurant TI, and budget-driven projects.

Frequently asked

What is structural silicone glazing?

Structural silicone glazing (SSG) is a curtain wall technique where glass is bonded to aluminum framing with high-performance silicone adhesive instead of an exterior aluminum pressure cap. It produces a flush, all-glass exterior appearance.

Is structural silicone glazing allowed in HVHZ?

Yes, with one major caveat: HVHZ jurisdictions (Miami-Dade, Broward, parts of Palm Beach) require structural silicone joints to be factory-bonded, not field-bonded. The bonded panels then install on-site as pre-assembled units.

Is structural silicone glazing reliable long-term?

Yes, when properly designed and installed with documented silicone products (Dow 995 or equivalent) and qualified installation. The technique has been used on commercial buildings since the 1970s with documented long-term performance.

When should I NOT use structural silicone glazing?

Skip SSG on basic retail TI, restaurant TI, budget commercial, and projects where the architect did not specifically request the flush all-glass appearance. The cost premium is hard to justify on standard commercial work.

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