The LWF Blog

Fire Safety Engineering for Design – Building Types & Fire Precautions – Part 17

February 22, 2021 11:50 am

LWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 16, LWF looked at building types and fire precautions, as well as how to address new occupancy types and how building height can have fire engineering implications. In part 17, we will continue discussing building height.

A tall building has a greater level of risk than a low-rise building, even though the probability of a fire occurring is not increased. However, as the consequences of a fire in a high-rise building are more severe, it is necessary to consider options to mitigate the level of risk and the potential for fire spread and fire damage should a fire start. In itself, this does not preclude certain types of occupancy, but the mitigating measures could be prohibitively costly.

In very tall buildings, phased evacuation is often used instead of simultaneous evacuation. Phased evacuation is where certain floors of occupancy are evacuated in sequence, commonly depending on the floor of fire origin. While a simultaneous evacuation requires all persons in the building to be able to evacuate at the same time, the implications for fire safe building design could be considerable; the width of stairways in a high-rise simultaneous evacuation building would be likely to put off most designers and building owners from pursuing this idea.

Phased evacuation can allow the occupants of the floors most at risk from the fire to evacuate, while increased fire protection measures can provide an environment in which smoke and flame spread is minimised and the fire is able to be extinguished before the remainder of the building is at risk.

The environment outside the building will affect the fire precautions inside too. Where firefighters are unable to set up at the building perimeter and undertake firefighting activities from outside, they must be given suitable access to the building, most commonly in the form of firefighting shafts. A protected firefighting shaft allows firefighters safe access to enter and climb stairways through the floors of the building, and a place from which to set up a forward attack point to carry out operations. A firefighting shaft will contain either a dry riser or wet riser, depending on the buildings height.

In part 18 of LWF’s series on fire engineering, we will continue discussing firefighting and fire engineering in tall buildings. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.

Lawrence Webster Forrest has been working with their clients for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 0800 410 1130.

While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.