Investigations after fires

2025-04-07 Academic News
Investigations after fires


Anders Arnhus

Text: Anders Arnhus,
Senior consultant at PiD Solutions AS


A fire broke out in a municipally owned and operated terraced house. The terraced house consisted of a total of 5 apartments with a living area of 60 m2. The building was built in 1991, in accordance with the building regulations of 1987. The fire quickly spread to a neighboring apartment and then to two other apartments in the terraced house, one apartment only suffered odor damage.

The problem of extensive fire spread beyond the fire-affected apartment in terraced houses is known from previous investigations that PiD Solutions AS has carried out on behalf of insurance companies. Our assignment today was to examine the building and map fire barriers and, if possible, describe current spread paths from the fire-affected apartment to other apartments.

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Investigation of the fire site

In such an investigation, it is important to collect relevant information about the construction method and about the fire barriers in apartment walls, - in cold attics, - rafter solutions vs. roof ventilation, etc. For us fire engineers, it is also an important learning arena to investigate real fires so that we can include this knowledge in our work as fire consultants.

We want to inspect the fire site as soon as it is released after the police’s crime scene investigations have been completed. It is important for us to see how the fire has affected load-bearing structures and the fire barriers, we record what the wind conditions were at the time of the damage and look for traces of wind-induced spread.

In fires that we have investigated, we see that the wind conditions have in some cases had a major impact on where and how the fire has spread in the building. The impact of the wind is interesting to include in the evaluations after investigations, as it turns out that fires can spread with the help of wind forces earlier than expected. Wind conditions are not included as a factor that must be taken into account according to requirements in the building regulations or other fire regulations, even though wind can have a major influence on the spread of fire.

Further work after the inspection

After the inspection, we are continuing to collect supporting material for the report. In this case, we have not concluded at the same time as the inspection, it is important to assess and test, as far as possible, different hypotheses for the mechanism that has led to the development of the fire in this specific fire. The fire department’s efforts, the number of crews, the supply of extinguishing water, etc., and the situation when the fire department started the extinguishing effort are also of great interest to have access to in an evaluation. Here, conversations with emergency crews from the fire department and photo and video material will be of great use.

Evaluation and conclusion

Our assignment is to evaluate this specific fire and to describe the spread routes. We will also point out the regulatory shortcomings in fire protection that have been uncovered that may have had an impact on the outcome of this fire. It is also important for us to point out that the spread of fire beyond the apartment where the fire started cannot necessarily always be explained by fire-technical shortcomings. Fire in buildings is a complex phenomenon that depends on many different variables, some with synergistic effects, other effects counteracting each other.

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