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Understanding Fire Rating

I was working on a project for our new Hyg-ie-Clad range when I found myself confused with all the numbers and letters presented on our fire ratings. So a colleague who has decades of experience in our industry, shared his knowledge with me. And now I’m sharing with you…
Just to give more context, we have 2 fire ratings for our Hyg-ie-clad: C S3 D0 and B S3 D0.

Per his explanation:

"Let’s first explain the FR reference, below you see letters and numbers example C S3 D0 or B S3 D0

All products are now under an EU standard, the top being A, next B, next C, next D next E etc.

A or B or C etc = denotes where on the scale the product sits reference fire behaviour, so concrete for example, has an A level i.e. you cannot burn concrete.

The next code you see is S and a number so our product is S3 this relates to ‘smoke’ and the level of smoke that is emitted in a fire - the lower the number the better.

The next code you see is ‘D’ and a number so our  product is ‘D0’ this relates to drop and the level of particles that can drop from the product when burning, the lower the number the better.”

Going a bit deeper, the PU Fire HandBook explain the Euro-classification.


Under the European classification system for reaction to fire as defined in the standard EN13501 part 1, building products are tested for reaction to fire and divided into seven Euroclasses:

  • A1 and A2
  • B, C, D, E
  • F for materials for which performance has not yet been determined or failing Euroclass E criteria

The classification of PU insulation can range from B to F depending on a variety of factors, including types of facings, the formulation used and the end-use condition. Further classifications are used to indicate smoke production (s1, s2 and s3), and burning droplets (d0, d1 and d2). PU can achieve anything between s1 and s3 for smoke development, again dependent on formulation, facings, and end-use condition, but as a thermo-set material it does not produce droplets and therefore always achieves d0.

In a summary,

There are 7 reactions to fire classification levels available.

This part determines how much a material contributes to the spread of flame:

  • A1, A2: Non-Combustible Materials
  • B, C, D: Material very limited to medium contribution to fire.
  • E, F: High contribution to fire.

The ‘s’ part relates to the total smoke propagation, during the first ten minutes of exposure:

  • S1: a little or no smoke
  • S2: quite a lot
  • S3: substantial smoke

The ‘d’ part is about the ‘flaming droplets and particles’ during the first 10 minutes of exposure.

  • D0: none
  • D1: some
  • D2: quite a lot

And you, have you ever struggled understanding fire rating?

Question about our product's fire ratings? Get in touch with us!

Naue Tunes,
Digital Marketing Assistant.