Concrete: The Non-Combustible Material for Structures
Concrete: The Non-Combustible Material for Structures
Concrete does not burn – it cannot be ‘set on fire’ unlike most other materials in a building and it does not emit any toxic fumes when affected by fire. It will also not produce smoke or drip molten particles, unlike many plastics and metals. Designing with a non-combustible material results in a structure needing simpler fire detailing and therefore having quicker construction programmes. The outcome of inadequate fire details, poor workmanship and modifications during occupation causing a fire risk are reduced when homes have a non-combustible structure.
Protecting our Communities
“Although occupier behaviour is a major reason for fires starting, the design and characteristics of a building will affect the potential for a fire to spread or to be undetected and, therefore, impact on the likelihood of the fire causing harm.” [1]
Much of design for fire safety is concerned with ensuring that people can escape from the building or structure, firefighters are protected and the fire cannot spread to other properties or areas. Current building regulations for England and Wales are written with these three aims and there is no requirement for protection of property or to minimise damage beyond this. Clients and project teams may choose to go beyond minimum requirements and choose to provide a higher level of protection against the hazards of fire either to further reduce the risks addressed by the building regulations or to protect property.
In the majority of applications, concrete can be described as virtually ‘fireproof’. This excellent performance is due in the main to concrete’s constituent materials (cement and aggregates) which, when chemically combined within concrete, form a material that is inert and, importantly for fire safety design, has relatively low thermal conductivity. This low conductivity means that the effect of fire is limited to the surface zones of the concrete with the middle of the element often unaffected. This also gives concrete excellent fire separation performance.
According to Government statistics [2] 60% of total household growth in England up to 2033 will come from households of age 65 or over. Designing beyond regulation, to protect an ageing population including vulnerable occupants, as well as occupants who are very young or with mobility limiting conditions, and therefore may need more time to escape a fire, are more reasons to choose a non-combustible material for structures.
Classification of ‘Non-Combustible’
Building materials can be classified in terms of their reaction to fire and their resistance to fire, which will determine respectively whether a material can be used and when additional fire protection needs to be applied to it. EN 13501-1 classifies materials into seven grades (A1, A2, B, C, D, E and F).
The highest possible designation is A1 (non-combustible materials). The UK also has a National classification system, which has ‘non-combustible’, ‘limited combustibility’, Class 0, 1, 2, 3 and 4 (with the lower number indicating lower combustibility, smoke emission or flame droplets).
Modern concrete and masonry are classed as A1 in the European system and ‘non-combustible’ in the National system, and do not need any further testing nor additional fire treatments.
Designers have a responsibility to consider fire as a real possibility that can affect people’s lives and livelihoods. Choosing non-combustible materials, such as concrete and masonry, for the main structure of a building, provides an excellent starting point for achieving a safer built environment for us all.
For more information on concrete’s performance in the event of fire, download ‘Concrete and Fire Safety’ from www.concretecentre.com/publications.
Get in Touch with The Experts
Andrew Minson, Executive Director
Andrew is Executive Director at MPA responsible for The Concrete Centre, British Precast and Modern Masonry. He joined The Concrete Centre in 2004 following 10 years with Arup in building engineering where he worked in multi-disciplinary teams developing integrated solutions. He is a Fellow of both the Institution of Structural Engineers and Institution of Civil Engineers.
He is currently chair of the IStructE Design Committee and member of the IStructE Engineering Leadership Group. He has a particular interest in sustainability. He was a member of the Buildings Task Group for the Low Carbon Construction review that led to the Green Construction Board, co-authored the Wiley publication Sustainable Concrete Solutions published in 2014 and chaired the IStructE Sustainability Panel. He is responsible for the Concrete Industry Sustainability Strategy.
Jenny Burridge, Head of Structural Engineering
Jenny is a chartered civil and structural engineer with more than 30 years’ experience in the construction industry. She has worked for Arup and AECOM designing award winning buildings in both the UK and mainland Europe. As Head of Structural Engineering she leads a team of engineers advising clients, engineers and architects on the most efficient and effective uses of concrete.
She is the UK representative on the CEN task group looking at revisions to the fire part of Eurocode 2 and chairs the BSI Advisory Committee for Engineering Design and Construction. She contributed to the Concrete Centre publication “Performance of Concrete Structures in Fire” and has been the UK member of the European Concrete Platform task-group on Fire and Eurocode 2 since 2010.
Tony Jones, Principal Structural Engineer
Tony is a Structural Engineer with over 25 years of experience in design, research and investigation of Concrete Structures. His role is to understand the impact of the Grenfell tower fire, and associated studies, on the concrete industry. In his previous role he provided advice to project teams on the design of structures for fire.
He chaired the advisory group for the BRE report “Concrete Structures in Fire performance design and analysis”. He has also been involved in the assessment of fire damaged buildings and provided advice to the emergency services in the immediate aftermath of the Grenfell Fire. He is the UK Head of Delegation on the Eurocode 2 design committee which is responsible for Eurocode 2.
