What Does a Fire Rating Like –/60/45 Actually Mean?

Ever looked at a fire rating like –/60/45 and wondered what it actually means? Many readers ask us this question, so we aimed to explain it clearly.

There are always three figures in a fire rating, always in the same order: structural adequacy / integrity / insulation. Each one tells you something specific about how a doorset performs under fire conditions.

• Structural adequacy (the first figure) often shows as a dash. That’s not a zero, and it’s not a fail, it means the criteria doesn’t apply. Structural adequacy measures whether a load-bearing element keeps holding up the building during a fire. A door isn’t load-bearing, so it gets a dash.
• Integrity (the second figure) is measured in minutes, 60 in this case. It’s the tested ability of the doorset to hold back flames and hot gases, to stay sealed and stop fire physically passing through the assembly.
• Insulation (the third figure), 45 minutes here, is usually the shorter of the two time figures, and for good reason: insulation measures how long it takes for the average temperature on the non-fire side to rise by 140°C above ambient. Holding back heat is a harder job than holding back flame, which is why this number is typically lower than the integrity figure.

Put together, both figures are demonstrated through furnace testing to AS 1530.4, the Australian standard for fire resistance testing of building elements.

Why does this matter in practice? If you’re specifying doors for a project, these numbers tell you exactly what performance you’re getting, and for how long, in a real fire scenario. Getting it right isn’t just a compliance checkbox, it’s the difference between a door system that performs as intended and one that doesn’t.