In December 2025, the University of Glasgow Fire Research Laboratory put our fire-retardant formulation through Britain's toughest surface flame test. Here's exactly what happened.

Read this first - it applies to one specific product

This result is for our fire-retardant (FR) formulation only - a special version with fire-retardant additives blended in during manufacture, available on request for schools, healthcare and high-occupancy settings. Our standard profiles do not carry this rating. If your project needs fire performance, you must specify the FR formulation.

View the real test result (Pdf) >

Fire testing sounds dramatic because it is. Independent researchers pointed a heat source at our material roughly as intense as 16 kitchen grills concentrated on one square metre, set the end alight, and measured how far the flames crawled in 10 minutes.

BS 476 Part 7 is the British Standard for "surface spread of flame" -how quickly fire travels acrossa material's surface. Materials are graded Class 1 (best) to Class 4 (worst). To earn Class 1, flames must spread no further than 165 mm - about the length of a ballpoint pen. Five sample panels of our FR formulation went in front of a 32.5 kW/m² radiant panel. Over 10 minutes, the flame spread on our samples averaged just 43 mm - shorter than a matchstick.

How far the flames got (10-minute test)

We passed with a margin of nearly 4 to 1. Source: University of Glasgow Fire Research Laboratory (ISO/IEC 17025 compliant), December 2025.

A second test (BS 476 Part 6) measured how much heat the material adds to a developing fire - its "fire propagation index". Lower is better, and anything at 12 or below meets the Class 0 threshold. Our FR formulation scored 9.0. In plain terms: it doesn't meaningfully feed or accelerate a fire. Instead of burning with an open flame, it chars, forming a stable carbon layer that slows the flames down.

Timber can reach Class 1 too - but only by soaking it in fire-retardant chemicals or painting on special coatings. Outdoors, those coatings weather away and must be reapplied on schedule, and if maintenance slips, so does the fire rating. Our retardant is mixed into the material itself when it's made. It's there for life: nothing to repaint, nothing to reapply, nothing to forget.

The FR formulation exists for projects where regulations or specifications demand rated fire performance: schools, kindergartens, healthcare settings and high-occupancy public buildings. For everyday gardens, parks and farms, the standard product is the right choice - and
the right price.

One honest trade-off to know about: the same heat resistance that makes the FR formulation fire-safe also makes it harder to recycle than our standard material. Our standard blend recycles easily with ordinary plastic recycling methods; the FR version needs more effort at end of life. We'd rather tell you that now than in the small print.

Get the full study

The complete University of Glasgow BS 476 fire study is available for specification packages, tender submissions and planning applications.
View the real test result (Pdf) >

Results apply to the specific fire-retardant formulation samples tested by the University of Glasgow Fire Research Laboratory in December 2025 and were achieved under BS 476 Parts 6 and 7 test conditions. The standard Miell Green product does not carry a fire performance rating. Surface spread of flame classification is distinct from certified fire-rated structural systems.