What Is Class A Decking?

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May 30, 2023

Class A decking is an external flooring application that has been fire-tested and deemed non-combustible and therefore safe and legal to use on high rise residential buildings above 11 metres.

The Class A rating is applied to any construction material based on their reaction to fire, in order to understand whether that material would contribute to the spread of fire or smoke in the event of a blaze. The flooring solution must earn a European Standard BS EN 13501-1 class A rating, meaning it has passed tests on its combustibility, burnability, and smoke ability.

It is important to note that both Class A1 and A2 can be specified on a high-rise attachment above 11 metres.

As stated above, the current UK building regulations state that high rise residential buildings (over 11m) must be constructed with non-combustible materials, including decking on balconies, roof and winter gardens, and other external attachments.

Those who do not specify Class-A rated high rise decking are subject to penalties. During construction, a fire inspector will be required to visit the site. If their inspection finds that incorrect materials have been used, they will suggest remedial actions. These can be simple or complex, depending on how much of the wrong material is in use. In order to avoid the costly penalties, specify non-combustible Class A decking from the beginning of a project.


How Are Materials Fire-Tested?

When discussing a material’s reaction to fire classification, we use the labels ‘non-combustible, ‘limited combustibility’ and ‘combustible’.

For UK regulations, fire testing includes products undergoing the BS 476 suite of tests which can be achieved through the National Classes. However, most construction materials also need a CE mark. This means that products must also be classified through the Euroclass system. 

The Euroclass Testing methods are stringent and closely monitored – thereby providing manufacturers, architects and specifiers with confidence and assurance.

Some products are naturally A1 rated – meaning that there is no need for fire testing. Products like this include mineral composite such as Zerodeck, aluminium, porcelain, concrete and natural stone – providing that they have not been ‘treated’ in any way – for example, use of glue, coatings, slip-resistance etc.

For example, Zerodeck provided by The Outdoor Deck Company is a mineral composite Class A-rated non-combustible decking system comprising of adjustable pedestals, joists, deckboards and accessories.


Why Is Class A Decking Important?

Since the 2018 change in Building Regulations, which were brought about by the Grenfell Tower tragedy, any high rise above 18m is banned from using combustible cladding. Similar regulations towards external flooring were also introduced, which means that high rise external flooring construction must specify class A rated decking systems.

Class A decking is extremely important in order to protect the lives and homes of people living and working in high rise buildings. However, non-combustible materials doesn’t have to mean specifiers are limited in their choice of design and style.

Class A external decking still comes in a variety of sizes, shapes, and colours. You can create stunning external flooring solutions with materials that are attractive as well as practical: weather-resistant and non-combustible.


Examples Of Class A Decking

There are many materials you could choose to build a fire-rated external flooring application, from porcelain, concrete and natural stone. As naturally non-combustible materials, these options would meet the conditions of the Euroclass fire-rating system and would be rated Class A.

Splitting Class A into A1 and A2 we can take a look at some construction materials for decking that would be approved. A1 materials are completely non-combustible whereas A2 materials have incredibly limited combustibility. Both types are considered non-combustible and are permitted on external applications on buildings of any height.

Mineral Composites are a great option for specifiers looking to achieve a wood-like finish which is still Class A fire-rated offering the best of both worlds for modern balconies or roof terraces.

Porcelain is a popular choice due to its versatility and durability.  Its impermeable scratch resistant surface means that it will never fade, stain or corrode. Additionally, it will never suffer from mould or moss. You can also achieve a variety of visual affects with porcelain tiles – from wood to concrete.

Stone paving is a great solution for those aiming to achieve a modern, yet rustic feel, with a subtle nod to our natural environment. The texture and appearance make the natural stone paving truly stand out.

Concrete is a great solution for those wanting to cover a large surface area. It is often the material of choice for those seeking a more practical solution.

Depending on what your aims are – and the purpose of application – each surface material listed above has its own unique properties, allowing you to produce eye-catching (yet safe) flooring, whether it’s a balcony, walkway, terrace, roof or winter garden.


Class A Decking & Subframes

Don’t forget that the whole system needs to be Class A rated, not just the decking surface material.

The subframe and joists must also be non-combustible, as each component works together to create a much bigger flooring solution. A stunning end-result that is Class A rated and safe for high rise buildings over 18m is the aim for many specifiers.



Zerodeck from The Outdoor Deck Company is a mineral composite Class A-rated non-combustible decking system comprising of adjustable pedestals, joists, deckboards and accessories.

The Outdoor Deck Company is one of the UK’s largest suppliers and installers of external high-quality decking.

Our extensive hands-on experience means we can provide you with the safest and most robust solution to whatever space you are working on.

We prides ourselves on being client-focused with a commitment to providing Specifiers with products that meets and exceed the required specification, alongside ongoing technical support that ensures every installation is on spec, on time and on budget.

If you have a project you would like to discuss, speak to one of our experts today.

Looking for expert advice? Speak to one of our team today...

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The Outdoor Deck Company provides technically advanced engineered decking and timber cladding systems for commercial and residential projects, with dedicated design and installation support and services. 


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