In the evening of the 18th January 2014 a fire started in a private home in the small municipality of Lærdal in the western part of Norway. There were strong winds, there was no snow on the ground, and there had been very little precipitation during January. The fire spread from house to house through the night and next morning and resulted in large material damages.
Background and objective for SP project
There was a considerable risk that the fire would spread to a large area comprising listed cultural heritage wooden buildings from the 18th and 19th centuries. Several fire brigades, the Civil Defence, Red Cross and many private volunteers put in a tremendous effort to control the fire and succeeded in protecting many residential homes and most of the listed buildings. 40 buildings burnt down, including 17 residential homes and 3 listed buildings. 681 people were evacuated during the fire and fortunately no one was seriously injured during the blaze.
SP Fire Research AS has performed a project for the Norwegian Directorate for Civil Protection (DSB) where the objective was to describe how the fire spread from the first house to the nearby buildings and further on. We have also investigated factors that helped restrict the fire spread, and factors that contributed to preventing buildings in critical positions from being ignited. Such factors may be connected to either fire preventive measures or to firefighting efforts.
The project has increased the understanding and knowledge of large fires where residential wooden houses are involved, and the results will be valuable for prevention of future large fires. Possible mechanisms of fire spread were assessed, e.g. fire brands that spread the fire hundreds of metres. The influence of building construction details and surroundings upon the fire development as well as effects of different efforts during the firefighting were also evaluated.
Several methods were used to investigate how the fire spread. A review of relevant literature was performed to get knowledge of the state-of-the-art within the field of fire spread in large fires. An inspection of Lærdal was performed. Despite the fact that this was about 12 weeks after the fire, we got an impression of the geographical area and got information about the fire from key people involved during the incident, and who described their experiences during the fire. A limited number of interviews of witnesses were conducted. Of special importance were the interviews with journalists and photographers who were present during the fire. Through them, and through searching on the internet, we had access to about 1500 photos and 10-20 videos that were analysed to identify where and when the fire spread.
The fire spread
Based on the analysis we drew a map of how the fire spread during the night, and another map indicating where the different fire spread mechanisms were important. The map showing the time aspects of the fire spread is shown in figure 2.Several factors led to the fast spread of fire in Lærdal: strong wind, dry weather, dry materials, and dry vegetation constituted optimal conditions for a rapid development and spread of the fire.
The most important fire spread mechanism was flying brands, but heat radiation and direct flame exposure also contributed. There were several occurrences of spot fires that started far away from the main fire area.
Effects of fire restricting measures
The efforts of the fire brigades were of vital importance, together with all the other organizations and volunteers who took part during the firefighting. An example of an effective measure is the fire brigades’ general firefighting with water. An extinguishing lance was used in one of the houses and this helped save the house from the fire. A tanker with extinguishing foam was brought from the nearby airport to the fire, and the foam was applied to undamaged buildings to prevent ignition. Farmers contributed by wetting the ground and extinguishing heaps of embers using water from liquid manure spreaders. In addition, volunteers and private persons contributed by raking away embers, extinguishing small fires, wetting houses and gardens etc.
It is not possible to point at one single measure among those mentioned that had a larger effect than the others; all of them were probably important factors in restricting the fire spread. Instances were observed where the fire had jumped over buildings where one or more fire restricting measures had been applied and ignited houses further away from the main fire area.
Based on the analysis of the fire spread, several fire restricting measures can be recommended. Owners of private homes can increase ignition resistance by embers and sparks through simple preventive measures and when building new houses or renovating existing ones siding and roof constructions can be upgraded. Fire brigades and other personnel who take part in firefighting can apply different techniques and extinguishing agents that are suitable to prevent further fire spread.
One important point is that fire preventive and restricting measures in areas with houses built of wood should be thoroughly planned. Many countries have guidelines available that help communities to make good plans for this type of fire preventive work. The Norwegian Directorate for Civil Protection (DSB) and the Norwegian Directorate for Cultural Heritage have published guidelines for fire protection in towns with wooden cultural heritage houses. These guidelines describe how a fire protection plan should be developed and which elements it should contain. The guidelines will also be relevant for fire protection of urban areas with wooden houses that are not regarded as cultural heritage. The guidelines (in Norwegian) can be downloaded from DSB’s web pages.
Need for more fire research
We see that there is a clear need for more knowledge about large fires both in built-up areas and in forests and wildlands. Several topics should be investigated:
- Is the risk of large fires increased in Norway because of changes in society and climate?
- How large is the fire exposure from houses engulfed by flames?
- What is the state-of-the-art of prevention and fighting of large fires in other countries? Is this knowledge relevant for Norwegian conditions?
- The effect of different fire safety measures should be investigated:
– simple measures for new and existing buildings
– fixed firefighting systems for exterior use
– different extinguishing media and techniques
– development of cost-effective extinguishing systems and fire safety measures
Credit: SP Fire Research