Following the well-publicised spate of fires within the waste and wood recycling sectors in the last few years the Environment Agency (EA) have been changing their regulatory approach to licence holders. The EA has been insisting companies implement increasingly stringent measures involving reducing stockpile sizes as a way of reducing the risk that a fire might spread to become a major incident. As a reaction to this many business have successfully argued that to mitigate the risk of a fire spreading a better approach is to construct fire walls which act as physical barriers preventing fires spreading.

However, whilst precast concrete has for many years been the material of choice when designing structures to withstand the spread of fire, there have in turn been a number of companies who have jumped onto the band wagon by promoting their products as being fire resistant when said products do not meet even the most basic of fire resisting criteria.
So for the avoidance of doubt here are some basic guidelines which might help you to avoid wasting significant capital on products which are falsely claiming some kind of fire resisting properties.

Building materials have various generic fire ratings from F (highly combustible) to A1 – which means they are totally non-combustible.

Products classified in A1 and A2 classes include cement, concrete, ceramics etc They will not burn, crack or give off noxious fumes regardless of the intensity of the fire or time spent being exposed to the fire.

However concrete can only be considered as Class A1 if it is made to recognised industry standards (concerning strength, provenance and traceability of raw materials, durability etc) and there are some important and simple factors to consider when you are specifying concrete fire walls

  1. Concrete is only Class A1 fire resistant if it does not contain any recycled materials or steel reinforcing (see below) Any company claiming to have Class A1 fire resistant characteristics who uses recycled materials in their concrete should not do so.
  2. Steel reinforced concrete panels have fire resistant characteristics too – but they are usually time limited (1 hour – 4 hours) depending on the thickness of concrete covering the steel reinforcing.  Under extreme heat the steel will eventually expand and crack the concrete causing the panel to fail.

So in summary –
Concrete is only Class A1 fire resistant if it does not contain any recycled materials or steel reinforcing. If your interlocking block supplier / manufacture uses recycled materials they cannot claim that the concrete is Class A1 fire resistant.