Tony Jones, Principal Structural Engineer at The Concrete Centre, addresses the need for fire safety regulations to take into account all known risks.
One of the longstanding flaws afflicting our building regulations is that our system is too reactive, built on responses to tragedy. The Ronan Point collapse, the King’s Cross disaster and latterly the Grenfell Tower fire: incidents like these leave indelible marks on our national consciousness and inevitably lead to an outcry for change.
However, we must ensure that alterations to regulations address total risk, safeguarding against all eventualities, rather than addressing only specific failings. This is essential if we are to tackle the industry ‘complacency’ criticised by Dame Judith Hackitt report into building regulations and fire safety. Simply put, we can’t wait for something to go wrong before moving to prevent it.
As Hackitt states, we should pursue a ‘holistic approach’ to meeting safety objectives. This means that the scrutiny which has rightly been applied to combustible cladding should now be broadened.
When it comes to protecting a building’s occupants and surrounding people and properties, there is little more important than structural safety. While the government has stated that it accepts Hackitt’s recommendation for “facilitating the prioritisation of fire and structural safety”, there is little indication of structural safety being prioritised. For example, it was not been included as part of Westminster’s proposed review of the current Approved Documents, the technical guidance that forms the bedrock of our building regulations.
Beyond ‘skin deep’
The current advice in Approved Document B3 (1) undermines the serious nature of any potential collapse with its ambiguity, stating only that a building’s stability should last for a ‘reasonable period’ in a fire. What a ‘reasonable period’ may be, of course, depends on several factors, including differing evacuation policies and specific uses – a high concentration of elderly or vulnerable residents will need more time to escape.
Moreover, Building Regulation 8 reminds us that designers must think not only of occupants but also of securing safety for ‘persons in or about’ a building. As it stands there is no difference in structural fire resistance requirements whether a building is isolated or urban, even though a collapse in a built-up environment could have far greater consequences. This should change to adequately reflect the industry’s responsibility and duty of care for communities.
While the use of combustible external elements, like cladding systems, has now been restricted, we need to avoid making ‘skin deep’ changes that don’t address risk built into the core of our buildings.
Current testing regimes for structural elements fail to consider any contribution to the fire load from the material being tested. This is despite some structural options, such as timber frames, being combustible and having the potential to feed a fire and impact its growth. Where structure forms part of the fire load, this must be considered to enable informed specification decisions.
In Scotland, regulations already prevent the use of combustible structural elements for new residential buildings above 18m without an accompanying complex fire safety engineering assessment. Westminster would do well to take notice of this approach as it as it considers its policy following the consultation on the technical review of Approved Document B.
Hackitt recently made it clear that she fears a ‘loss of momentum’ from waiting for the government’s response. Crucially, we shouldn’t be waiting for another incident to spur change. The time to take a proactive approach and address total risk is now.
This article first appeared in Infrastructure Intelligence.
By Tony Jones, Principal Structural Engineer at The Concrete Centre