How is fire-rated glazing tested and classified?

Fire-rated glazing is tested by building a full-size sample of the glazed system into a furnace wall and heating one side to a standard time-temperature curve while integrity, radiation and insulation are measured. The results are turned into a classification under BS EN 13501-2, such as EI 60, which applies only to the tested system within its field of application.

Which test standards apply?

Glazed screens and non-loadbearing walls are typically tested to BS EN 1364-1. Doors and opening windows are tested to BS EN 1634-1. The results are classified to BS EN 13501-2.

Older UK evidence may refer to BS 476 Part 22. In England, references to the British Standard route are being phased out of Approved Document B, so check what evidence your project will accept.

What happens in the test?

A specimen built exactly as it will be installed is mounted in a furnace. One side is heated following the standard fire curve, which passes about 840°C after 30 minutes and about 1,000°C after 90 minutes.

Thermocouples, radiometers and gap gauges record performance until the specimen fails or the test ends.

What is a field of application?

Test results can be applied to variations of the tested specimen, such as different sizes or orientations, only within rules set by the standards or by an assessment from a competent test body. Outside those limits the evidence does not cover the installation.

What is an assessment?

Where a project differs from what was tested, a fire test laboratory or competent body can issue an assessment, sometimes called a global or engineering assessment, which states whether the variation would be expected to achieve the classification. Assessments are a normal part of fire glazing evidence.

What should you receive?

Ask for the classification report or certificate covering the system, any assessments relied on, and the installation instructions. We include these references in every handover pack.

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