How do you identify fire-rated glass?

Most fire-rated glass carries a permanent etched or printed mark in one corner showing the product name, classification and sometimes the manufacturer. Wired glass is recognisable by its mesh. Unmarked clear glass in a fire-resisting wall should be treated as unverified until evidence shows otherwise.

Look for the mark

Check each corner of the pane on both faces. Marks may show the product range, a classification such as EI 30, and impact safety class. Photograph the mark with a ruler for scale.

Clues from appearance

Insulating glass is noticeably thick, often with several layers visible at the edge. Integrity glass may look like ordinary glass, which is why marks matter.

What a visual check cannot prove

Even correctly marked glass only performs in a frame tested with it. Identifying the glass is the first step; the frame, beads and seals need checking too.

When in doubt

If there is no mark and no record, assume the pane is not proven. A fire glazing survey can record what is there and recommend next steps.

Updated 09/10/2026. General guidance only; your fire strategy, designer and building control body decide what applies to a specific building.