Fighting fire in building design and construction

Chris Leese, Director MPA UK Concrete, comments on the critical role that building material specification can have on the fire-safety of commercial and multiple occupancy residential properties. 

The UK fire and rescue services attended over 73,000 fires in England alone in 2018.  More recently, a spate of serious fires has devastated multiple occupancy buildings and properties and put the lives of hundreds of people at risk.  Fires such as those at a Crewe retirement complex fire in August 2019 and Worcester Park in September 2019, highlight the ever-present risk that fire poses. 

Although it was extremely fortunate these resulted in no fatalities, we cannot afford for building regulations to ignore the risks of using combustible materials in structures.  It is time to rethink regulations and champion the use of non-combustible building materials that help to protect against every fire in every conceivable situation.  Materials such as concrete and (concrete) masonry perform well when faced with the threat of fire in comparison to combustible building materials including timber.

Fireproof

Concrete’s A1 rating under the European system of material classification means that in the majority of applications the construction product can be described as virtually ‘fireproof’.

Concrete has a relatively low thermal conductivity – or heat transfer – which enables it to act as a fire shield not only between adjacent spaces, but also to protect itself from fire damage.   Even when faced with searing temperatures over a prolonged period of time, the internal temperature of concrete remains relatively low.  This allows the material to retain its structural integrity, thereby reducing the risk of catastrophic damage or collapse.  

Take for example Tytherington County High School in Cheshire, where an arson attack on the premises caused widespread damage to the property. An adjacent lightweight structure which suffered extensive fire damage subsequently collapsed and had to be demolished and rebuilt.  Whereas, owing to the fire resistance of the concrete structure of the main school building, the classrooms within this wing could be repaired in time for the new term.

Fire defence and design

Residential fires – whether fatal or not – destroy lives.  It is unreasonable and unacceptable that fires in homes continue to wreak such devastation, despite being compliant with regulations designed to protect them.  Banning combustible external elements from at-risk buildings was an essential first step.  However, legislation continues to allow for combustible structures that suffer more damage during a blaze.

Tall buildings such as student accommodation blocks or retirement homes require higher degrees of fire resistance as they normally contain more occupants and it is often harder to tackle such fires.  Standard firefighting appliances can typically only reach 18m, anything higher requires specialist firefighting equipment.

When designing new high-rise structures, it is important to design the building so that in the event of a fire, residents can safely flee using a fire-proof route out of the property.  As a fire-proof material, concrete is uniquely suited to providing safe passage to residents to the nearest exit and a safe space for anyone unable to use those routes as its non-combustible qualities will prevent the spread of fire.

Counting the cost

Fire currently costs the UK on average £8 billion per year and considerably more in personal losses.  By designing buildings from the outset with fire safety at their heart and opting to construct them out of non-combustible materials, these financial and human costs can be dramatically reduced.  

Our immediate challenge as an industry should be to look beyond reacting to specific incidents and addressing the individual failings exposed by disasters such as Grenfell, and towards developing new, fit-for-purpose fire safety regulations that work for every fire in every conceivable situation.

Key facts:

1.    Concrete does not burn and is virtually fireproof
2.    Concrete does not add fuel to a fire, unlike combustible materials such as timber
3.    Concrete and masonry are effective fire shields
4.    Concrete does not produce any smoke or toxic gases in a fire
5.    Unlike steel, concrete and masonry do not drip molten particles, which can spread the fire