Product Overview

There are two main types of composite decking. WPC boards are typically made from between

55-60% recycled hard wood fibres and 40-45% recycled high- density polyethylene. They are a cost effective solution with a consistent finish. Most systems will use hidden clip systems to fix them, making for easy maintenance, etc. Alternatives composites are wood-free instead using a polyurethane resin blend. These are fixed using screws through the boards. Such choices are often at a considerable premium over WPC composites.

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 pendium tests (determines slip resistance), before and after accelerated weathering, 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 market place that grooved boards offer better rainwater dispersal. With less rainwater siting on the decking, slip resistance should therefore be improved.

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