In most types of buildings it is necessary to ensure that the structure of the building will remain in place for a reasonable period during a fire. That is to protect the people who are evacuating the building as well as to reduce the risk to any fire brigade who may be dealing with the fire. Some types of structure, such as reinforced concrete, inherently achieve a reasonable resistance to fire (although for longer fire durations, increases in reinforcement cover may be required). However, others, such as structural steel, often need to be protected by insulation to prevent the steel heating to the point where it collapses.

That insulation can be relatively expensive and can affect the physical appearance of the structure, so it is important to ensure that the insulation is not over-specified.

Conventionally, in most types of buildings, the amount of fire protection that is required is based on reference to a standard guidance document that states a specific fire resistance period based on the height and type of building. For example, Approved Document B would recommend that the structure supporting a 10m high office building should achieve 60 minutes fire resistance. The fire resistance period refers to a specific duration within a standard fire test furnace (such as BS 476: Part 20) and has no direct relationship to how long the structure would last in a genuine fire (this is a common misconception in the construction industry).

This approach is simple, but often results in major over-specification because it treats all structure in the same way irrespective of the fire risk on each element. For example, in some situations structure may be located in very low fire risk locations such as external to the building or in an atrium. Additionally, detailed predictions of actual fire severity often result in much lower fire severities that those required by Approved Document B.

Structural fire engineering is a technique where the actual fire severity can be predicted for each location within the building, and calculations carried out of the impact of that fire on each element of structure. This can often result in very significant reductions in the amount of fire protection that is required for the structure, and major cost savings.

ASEC includes experts in structural fire engineering and have extensive expertise in applying it to a wide range of buildings.