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In turn, building professionals have seen increased pressure from clients with a new vested interest in the fire safety of their building. Those responsible for meeting RRFSO stipulations want to know that every aspect of a building can be relied upon should fire break out, and the suitability of building envelope elements such as roofing and cladding is no exception.

Composite panels are widely used as part of building envelope construction, and have been subject to extensive fire safety testing. This has helped to clarify the performance characteristics of different panels and their safety in relation to other products, but there is still some confusion over the fire performance of core materials used in these panels. It is hoped that this article will help to clear any confusion surrounding the suitability of composite panels as a fire-safe external envelope component.

One of the most reliable and stringent fire tests for composite panels is LPS 1181 from the Loss Prevention Certification Board (LPCB), which is used to test both external (Part 1) and internal (Part 2) applications. Although the UK government and the EU have developed important legislation to assess the fire safety of building materials, assessment methods from organisations such as the LPCB and FM Global are widely regarded as providing a fuller evaluation. These independent assessments offer an important perspective and play an influential role in specification.

Within LPS 1181 Part 1, a number of ratings are used to indicate performance. The EXT-B grade signifies that a product has achieved a certain level of resistance to fire propagation, whilst a product that receives an EXT-A rating has achieved EXT-B demands and has also passed a test for fire resistance. Ratings EXT-A15, EXT-A30 and EXT-A60 signify the length of time a product has maintained its insulation and integrity.

Since 2004, PIR has been used as the insulation core of the majority of UK-produced external composite panels. Although testing achievement varies between manufacturers, PIR-cored panel products have had an EXT-A30 rating confirmed by the LPCB, whilst testing of the same products for an EXT-A60 rating has been completed and is pending confirmation.

In achieving LPS 1181 approval, PIR-cored composite panels also have proven fire resistance for up to sixty minutes. Considering that products meeting LPS 1181 Part 1 EXT-B are regarded as sufficient for the vast majority of buildings, the fact that PIR-cored panels are capable of achieving EXT-A30 and potentially EXT-A60 suggests there should be little doubt over fire safety.

Some arguments against the suitability of composite panels group PIR with other foam insulation materials, such as Extruded Polystyrene (EPS), which have not achieved the same levels of fire safety certification. A distinction needs to be made here, as there are crucial differences between the fire performance levels of these products and grouping them together does not give a clear or truthful message.

A question remains as to what degree fire performance should be an issue above and beyond Building Regulations compliance, LPCB approval and endorsement by fire professionals. Composite PIR-cored panels have all of these merits and provide more than sufficient fire safety for ordinary applications.

With demands placed on envelope performance by the Building Regulations Part L and the impending Energy Performance Certificates, a balance needs to be struck between ensuring fire safety and maintaining other performance requirements such as energy efficiency.