Tall buildings are the talk of the town. In London, plans have been approved for several landmark buildings which will transform the skyline of the city. They are all innovative, striking and ambitious and they all present great challenges in engineering.
Each tall building presents its own problems for the fire safety engineer. But subject to close inspection by safety regulators on one side, and pressed by the constructor with an eye on costs on the other, the fire strategy can easily be compromised. Basic passive fire protection, invisible when the building is complete, can be seen as the soft option for cost cutting.
Mere compliance with current regulations for fire safety is not enough, as they do not allow for the massive structures now being planned – all buildings that are more than 30m high are treated the same in Approved Document B, which is absurd, because all such buildings are treated as individual cases by the designers and regulators.
At the design stage, trade-offs are considered – in construction, substitutions are made – cheaper products can end up in a situation for which they have inappropriate certification and installation by unqualified operators can lead to failure of vital elements of passive fire protection (PFP).
The PFP coating of the steel trusses in New York's World Trade Center failed to attach properly, leaving many areas unprotected. We don't know whether that particular problem was the result of cost cutting at the installation stage, but we do know that such things happen.
Given the scale of a tall building, it might seem attractive to save a few pounds on, say, fire doors, but specifying and installing the best available can potentially save much more.
The cost savings from a few fire doors, seals or stoppers is tiny compared with the damage caused by a fire that cannot be contained.
The fire safety engineer (FSE) will make a case in the fire strategy for certain elements and if these are not installed exactly as he envisages, that strategy may be compromised.
It is essential that the fire safety engineer's strategy is understood by all in the contract chain and passed on to the owners and occupiers who must maintain it as originally envisaged. If fire loads, occupancy levels, business activities or other major elements change, the effect on the strategy must be considered.
Tall buildings represent high-value investments with high-value contents. But if a fire occurs, the preservation of life is paramount. There is also the cost of destruction, disruption and business continuity as well as the environmental impact from the major fires that could develop.
But which aspect of a potential attack should the designer address? Blast? Impact? It is not possible to protect against every perceived threat; better to protect against the threat we can be sure of – fire. Tall buildings make news – let's make sure it is for the right reason.
- David Sugden is chairman of the Passive Fire Protection Federation