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Cladding Fire classifications explained

It’s important to understand the difference between cladding fire classifications, the laws surrounding them, and what they mean for your project when choosing which building materials to use.

Safety must always come first- whether it’s for your home, place of work, your child’s school, or elsewhere, it’s crucial to use materials which are regulated and approved under the European standard of fire safety.

Following the tragic Grenfell Tower fire in 2017, the existing building regulations in place were amended, to ensure that all materials used for cladding were compliant and, ultimately, safe for use.

Here, we explain exactly what those regulations are and break down the classifications used to determine a material’s reaction in case of a fire, so you can understand the terminology and clarify that the safest cladding is being used for your development.

Amendments to building regulations

In 2018, the building regulations were amended to stipulate that any material used as external cladding for relevant buildings over 18m high must have a European Classification (which we explain further on) of A2-S1-D0 or higher.

‘Relevant’ buildings refer to any buildings over 18m in height above ground level which contains one or more dwellings, an institution, or residential spaces.

European standard of fire safety

Introduced in 2000 by the European Union, in a bid to ensure consistent levels of quality across the whole of the EU, the Euroclass system classifies a material’s reaction to fire.

Additionally, it pinpoints a number of characteristics such as flame spread, heat release, ignitability, and smoke production.

What are the designations?

Fire behaviour 

This classification establishes the contribution of a material to the behaviour of fire.

The classifications are broken down as below:

  • A1 = non-combustible materials
  • A2 = non-combustible (Scotland) and limited combustibility (England and Wales)
  • B, C, D = ranges from very limited to medium contribution to fire
  • E, F = high contribution to fire

Smoke development 

This outlines the amount of smoke that is emitted for the first 10 minutes of the material being exposed to fire:

  • S1 = little or no smoke
  • S2 = quite a lot of smoke
  • S3 = substantial/heavy smoke

Flaming droplets/particles formation 

This designation focuses on the amount of flaming droplets and particles which the material produces in the initial 10 minutes of exposure to fire:

  • D0 = no droplets
  • D1 = some droplets
  • D2 = quite a lot

So as per the amended building regulations in 2018:


A2 = non-combustible (Scotland) and limited combustibility (England and Wales)
S1 = little or no smoke
D0 = no droplets

British standards- Class 0 Fire Rating

Lastly, all materials used in the UK for cladding must also meet specific British standards and are rigorously tested to determine they are safe for use. To be deemed as such, they must achieve the Class 0 Fire Rating. So, what exactly is that?

The 20-minute test that the material must undergo measures the amount of heat that the surface is giving off.

The measurements over the 20-minute period are then put into a special formula and an index rating is concluded. To achieve a Class 0 Fire Rating, the index rating must be 12 or less.

Once a material has been given a Class 0 Fire Rating, it has been approved for use, and will protect surfaces from the spread of fire as well as limiting the amount of heat released from the surfaces.

Final thoughts

To ensure fire safety and that the materials being used for your project are compliant with British and European standards, opt for a material with A2-S2-D0 or above, such as cedral cladding.

We highlight five things you probably didn’t know about cedral cladding in this post, [link to other post once published] which sums up why it’s a great option for your exterior cladding.

Unicorn Windows is committed to delivering the highest quality of products to our customers, and all of our products meet the standards and regulations mentioned in this article.

Contact one of our team today to find out more about our cladding and guttering options available.