What Thickness of Glass Flooring to use?
The Glass Floor Thickness Dilemma: Why 25.5mm Isn't Always Enough (And When It Surprises Us)
When investing in a stunning walk-on glass floor, the primary question from clients is always: "How thick does the glass need to be?" The required specification is not just about aesthetics; it’s about meeting structural safety standards and providing absolute peace of mind.
The Standard Rule of Thumb
Getting the specification right is complex, but we have established guidelines based on years of experience. For most domestic applications, we generally advise clients that spans up to 1000mm can be safely covered with 25.5mm structural laminated glass. However, for larger openings or longer spans, we typically recommend stepping up to 33mm glass or thicker. This simple rule helps manage expectations and costs early in a project.
The Challenge of Large Spans and Restricted Frames
This standard guidance is put to the test when structural constraints are tight. We recently encountered a client who needed a particularly large glass panel for their floor, measuring 1628 x 1522mm but had significantly restricted depth for the supporting frame. The glass specification proposed was a 25.5mm toughened laminate , comprising 12mm nominal thickness glass, a 1.5mm plastic interlayer, and another 12mm nominal glass ply.
To ensure we could meet the minimum safety requirements while working within the client’s spatial constraints, we obtained a stress and deflection analysis directly from the industry leading authority; The Glass and Glazing Federation (GGF).
The Surprising Engineering Result
The analysis confirmed that the proposed 25.5mm specification had adequate capacity to withstand the specified loads. The variable UDL of 2.5kN/m2 produced a calculated bending stress of 24.35N/mm2, which was well below the allowable design strength of 77.5N/mm2.
Furthermore, the glass passed the stringent deflection serviceability check. The industry standard allows a deflection limit of span/250. For this panel, the calculated deflection of 4.01mm was safely within the 6.25mm allowable limit.
Our Final Recommendation: Prioritize Peace of Mind
While the calculations confirm the absolute minimum required thickness, proving the panel's structural viability and its ability to maintain integrity through the inclusion of a redundant glass ply, our final advice is this: always prioritize peace of mind.
Although the 25.5mm specification technically passes the deflection limit, going thicker when budget and frame depth allow provides an extra margin of safety, virtually eliminates deflection, and ensures long-term confidence in your floor. Always consult with us to verify the specifications for your unique opening.