Published: May, 2021

What Is Class A Decking?

For a product to meet Class A fire rating specifications it must undergo tests to prove that when subjected to flames it will not ignite, combust, give off toxic fumes or dense smoke, and not form burning droplets that can cause fire to spread.

  • What Is Class A Decking? image 1

In construction, a deck refers to a platform resembling a ship’s deck, adjacent to a house or other building and usually supported by an open framework raised above the ground. The deck surface – known as decking – is traditionally timber planks either placed directly abutting each other or with narrow space in between to help drainage.

The popularity of decking has spread to balconies and roof spaces, transforming drab or disused areas into havens of calm and relaxation.

Composite decking – a combination of wood fibres and plastic resin – is a more recent development that gives the warmth and appearance of wood but with greater resistance to rot and weather.

Unfortunately, neither of these materials scores very well on fire safety, and although they are still acceptable for use at ground level or on low-rise buildings (five storeys or less), the Building (Amendment) Regulations 2018 state that all materials installed externally on a high-rise residential building must comply with Euroclass Class A fire rating.

At the time of writing, the definition of high-rise in Scotland is 11 metres or more and 18 metres or more for the rest of the UK, although discussions continue on whether the rest of the UK should also change to 11 metres.

What is Class A fire-rating?

For a product to meet Class A fire rating specifications it must undergo tests to prove that when subjected flames it will not ignite, combust, give off toxic fumes or dense smoke, and not form burning droplets that can cause fire to spread.

If all these conditions are met, the material will be Class A1 approved. If most conditions are met, with only minimal fume or smoke emissions, it may still satisfy Class A2. Both subclasses are allowed within the requirements of the regulations.

Of course, the natural properties of many materials used in decking systems and roof terraces – stone, concrete, porcelain, aluminium and steel – mean they meet Class A1 without any need for testing. Powder-coating compounds used on aluminium and steel contain no volatile organic compounds (VOCs) so they still fall within Class A2.

When designing and specifying materials for a decking structure on a balcony or roof space, it is important to remember that all components of the structure must comply with regulations. This includes the frame on which the deck sits, the pedestals that raise the frame above the balcony or roof, and any fixtures used to hold it all together.

Use of non-compliant materials will result in costly removal and replacement with compliant products, and possibly even financial penalties, so it makes sense to know what products are Class A rated and to specify them from the start.

If you’re still unsure about what qualifies a material for a Class A rating, we regularly run a Creating a Safe, Class A Terrace training seminar within our Continuing Professional Development (CPD) program for architects, designers, specifiers and installers. Call us today and book a place.

How are materials given a Class A fire-rating?

To establish a material’s fire rating, it is exposed to flame and observations are made on how it reacts.

  • Does it ignite?
  • Does it emit toxic fumes or smoke?
  • Does it form burning droplets?

If the answers to all three questions are no, the product will be classified as A1. If the material does not ignite, fume or smoke emissions are too low to be hazardous to health or obstruct vision and droplets are too small to cause a fire to spread, the material may still be classified as A2.

Why is it so important to use Class A decking?

Fire safety is now taken very seriously in the wake of the 2017 Grenfell Tower fire – 72 lives were lost and the tragedy became a catalyst for change that resulted in the Building (Amendment) Regulations the following year.

Investigation after the fire revealed that the tower’s original non-combustible cladding had been replaced with a cheaper, combustible alternative during renovation works. This facilitated the rapid spread of fire up the outside of the building. Given that balconies and roof spaces can often become life-saving exit points in the event of a fire, the regulations were extended to include all materials used in these areas.


What design choices do I have with Class A decking?

Although real wood and composite decking is unacceptable for the balconies, terraces and roof gardens of high-rise residential buildings, there are still plenty of options to choose from.

If you want to stay safe and specify only Class A1 products, you can choose:

  • Atria 20 mm-thick porcelain tiles. Choose from 44 elegant wood- and stone-effect finishes each available in up to 14 tile sizes to create intricate patterns.
  • Farrino 26 mm-thick porcelain tiles. Choose from five highly realistic woodgrain finishes as 145mm (W) and 1202mm (L) planks that give the impression of traditional timber decking.
  • Novento wind-resistant porcelain tiles - Launching soon!

All these products are also extremely durable, stain-resistant, scratch-resistant and non-slip you could alternatively use real stone or concrete pavers, but bear in mind their disadvantages:

  • They aren’t a strong as porcelain tiles so will need to be thicker/heavier to bear loads. This will make them more expensive to transport to site and install.
  • Unless treated, they are more prone to staining. If you choose treated stone or concrete, make sure the treatment doesn’t affect their Class rating.
  • Being porous, they absorb and retain water. This can cause cracking in low temperatures and encourage the growth of moss and lichen, which will make the surface very slippery when wet.

Powder-coated extruded aluminium decking is also an option, although this can only be given a Class A2 rating due to the coating.

Important: powder coating contains no volatile organic compounds (VOCs) which makes it fine for Class A2. Avoid other paint finishes unless you can be absolutely sure they are VOC free and meet the other requirements for Class A2.

One problem with powder-coated aluminium is that the surface is more prone to scratching, particularly in high-traffic areas) and will look unsightly if the colour of the coating contrasts with the natural aluminium underneath. Some colours are also more prone to fading when exposed to the UV in sunlight.

Don’t forget the subframe!

For a deck or terrace system to comply with regulations, all components used in its construction must be Class A1 or A2 rated. This includes the subframe that holds the deck in place and the pedestals that lift it away from the balcony or roof to allow for drainage, uneven surfaces and protrusions such as drains and vents.

Our Preventa system is comprised of two main components:

  • Raaft Class A fire-rated extruded aluminium support joists use a modular construction to quickly and easily create a strong but lightweight platform that takes high footfall in its stride while putting minimal strain on balcony and roof construction.
  • Preventa pedestals are also Class A fire-rated and as they are height-adjustable they eliminate the need for additional shims and packers to achieve a level, stable platform. This is important, because many packers used by contractors are made from materials that are not Class A compliant.


If you would like more information on our range of products, email [email protected] or call us on 01580 830688.

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Mustard Wharf

Mustard Wharf required terrace systems that are attractive, durable, functional and fire-safe. Farrino porcelain decking and Preventa pedestals was the solution.

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