Class A Decking

Since the Hackitt review and the following combustible cladding ban the industry has been struggling to understand and adapt to the changes in regulation.

Balconies are of course included in the ban on combustible materials on the exterior of buildings over 18 metres including components like soffits and decking.

All decking must now be class A and be fully non-combustible. Our supplier MyDek provides aluminium decking in a range of finishes which are all fully compliant with government regulations.


Sapphire has had experience with and installed on Cassette® balconies many of the WPC and wood-free composite decking boards on the market.

As part of the extensive third-party Cassette® testing, we tested multiple decking options in pendulum tests (determines slip resistance), before and after accelerated weathering, the structural performance of decking, etc.

One of the selection considerations is the PTV (Pendulum Test Value) achieved, these are categorised as:

  • 0-24: high slip potential
  • 25-35: moderate slip potential
  • 36+: low slip potential

Sapphire had tests carried out by a UKAS accredited test house in a lab with a temperature of 21°C. The Pendulum values from these tests are shown below.

Whilst there are many options of composite boards, Sapphire prefer to supply their own extruded composite board which has been extensively tested and offers a wide range of standard colour and grains, uses a hidden clip system and is cost effective.

In our experience, darker colours are most common, used in conjunction with a B1 – brushed finished. It is generally considered in the marketplace that grooved boards offer better rainwater dispersal. With less rainwater sitting on the decking, slip resistance should, therefore, be improved.

A key consideration post-Grenfell is decking compliance with the combustible cladding ban. All materials used on the exterior of buildings over 18 metres must be non-combustible. Download the full whitepaper on the ban to learn more.

We are proud to be UK’s only distributor for Enjura WPC decking.


Hardwood decking is a more expensive option than softwood, which has a closer grain and fewer knots. These both offer extra durability and less maintenance.

A close natural alternative to hardwoods includes thermowoods, like Lunawood®, which are often chosen as these woods have been thermally modified to enhance the chemical, and physical properties of the timber, particularly for durability. Thermowood is produced by heat treating selected timbers, such as; Scandinavian Redwood (Pinus Sylvestris).

Hardwoods can often have more of a diverse grain pattern and natural colouring than softwoods do. Fixings would usually be stainless steel screws through the boards.

With the introduction combustible cladding ban, hardwood decking cannot be used on building exteriors over 18 metres.

Soffits remain a necessity on balconies for a range of reasons from the ease of drainage, aesthetic benefits and improved fire safety.


Softwood decking is the cheapest natural wood option with a reasonably consistent grain and colour, it does, however, tend to contain a lot of knots.

Softwood can often appear to be a very cost-effective solution. However, in our experience, softwood tends to twist and warp considerably, especially if the decking is relatively thin. knots have also been a considerable cause of issues, over relatively short periods of time. Softwood boards are readily available and options also include ones with anti-slip inserts added for extra grip. Boards are typically fixed down using stainless steel screws.

Since the introduction combustible cladding ban, softwood decking cannot be used on building exteriors over 18 metres.

Soffits remain a necessity on balconies for a range of reasons from the ease of drainage, aesthetic benefits and improved fire safety.