Fire Safety and Performance in the Roofing Insulation Industry

Published – October 2023

Although always being a key part of our industry, the drive for fire safety and performance in construction has accelerated, following the unfortunate and devastating event of Grenfell. There has been a seismic shift in insulation requirements for the roofing industry, not least due to building regulation changes. Adaptability has always been key in the roof insulation industry, never more so than now, with our requirement to keep abreast of building regulations and product options to give clients the optimal solutions.

As a flat roof insulation specialist, we must understand fire classification of materials themselves as well as building regulations, the most poignant one for us currently being Broof (t4). The individual material components have fire classifications and Broof (t4) is a system test for warm and inverted flat roof systems.

Material’s combustibility is classified according to the European Classification Standard BS EN 13501-1. These classifications give manufacturers the framework for rating products accurately, describing how they react to fire. These reactions are then translated into classifications and assigned to the individual product. A1 and A2 being non-combustible and  B-F are classified as combustible in ascending order.

UK Building Regulations have established rigorous standards and guidelines for fire safety in roofing systems. Broof (t4) specifically assesses the external fire exposure resistance of roofs, focusing on their ability to withstand flame penetration and prevent the spread of fire. Compliance with Broof (t4) is an essential requirement in meeting the fire performance standards.  

While there is technically no such thing as a truly non-combustible flat roof system and there has not yet been a particular call for it in the industry, there has been a distinct clamour in the industry to provide the flat roof insulation (including insulated upstands) to be non-combustible. Interestingly, both combustible and non-combustible insulation materials can be used on a flat roof system and still achieve Broof (t4) regulations.

In terms of non-combustible upstands, it is deemed necessary for the adhesive used within them to be minimally A2 non-combustible. This however brings about an anomaly in non-combustible insulation system being that if you have a bonded system, it would seem logical for the bonding adhesive to be minimally A2 also. Currently, this is not a requirement.

CTF Insulation see the future of our industry progressing in a regulatory direction for the flat roof insulation system itself to be truly non-combustible in every element. This would include the adhesive in warm roof applications and WFRL (water flow reducing layer) in inverted roof application.

As an insulation specialist, we comply with Broof (t4) but strive to supply insulation systems with all component parts classed as non-combustible. Looking to the future, we are making significant and exciting developments in our product range to allow us to supply truly non-combustible flat roof insulation systems.

We see terraces and balconies as a challenge to this, as often with non-combustible insulation, comes a “trade-off” with overall insulation thickness. On standard insulation, Cellular Glass and Stonewool are the materials to be used to achieve the A1 non-combustible classification. However, compared to the optimal combustible insulation option (for example PIR), an average of 60% greater thickness of the non-combustible insulation materials is required, compared to the combustible insulation (bases on a u value of 0.10 W/m²K). The overall thickness of an insulation system currently has to be compromised if non-combustibility is required.

We believe there may be a solution to that in the future also.