Fire Investigation and Evidence PreservationIntroductionThe basic objectives of any quality fire scene investigation is to establish and document the origin and cause of the fire and learn what human actions or failures contributed to ignition and fire development. However, in an extensively fire-damaged building this can be a complicated undertaking considering the danger of collapse and other hazards that will confront the investigator. Sound judgement, tenacity, endurance, good observation skills and memory, well-developed technical skills and substantial experience interpreting fire damage patterns are essential qualification for a fire investigator.
The focus of this research is to recognize the signs, symptoms and causes of collapse. It will also include hazards that may encounter during the investigation and proper approach to information gathering and evidence preservation. Finally, it will explore the various indicators of arson and prevention methods that property owners can apply. Fire InvestigationFire investigation involves examination of the fire scene to determine the cause, origin, development of fire, and laboratory analysis of samples recovered from a fire scene. Fire investigator should have an understanding of a variety of concepts such as the basic practices and methodology, and frequently used materials in buildings and their effect on and reaction to fire development, and the required setting for a fire to be started and sustained (Redsicker and O’Connor 1996, p. 29).
Investigators should be aware of burn and smoke patterns, their interpretation, and various types of fuel package, their auto-ignition temperatures, behaviour in fires and the level of heat release, which they may produce. Importantly, they are knowledgeable of sampling protocols, packaging and related activities (Daeid 2004, p. 4). Signs and Symptoms of CollapseBuilding failures that can be observed on the fire scene include smoke or water through walls, soft floors, small partial collapse, and unaligned walls.
Intrinsic structural instability of a building aggravated by fire is a common sign of likely collapse. Another is the non-masonry supporting elements’ failure where parts of a building masonry depend. Retained water added to live load because of fire fighting operations. The disintegration of masonry wall because of intense heat and the collapse of another building into the structure under investigation (Brannigan 1992, p. 156). Normally, building elements and materials show signs of potential collapse.
For instance, poorly made bricks absorb moisture and can deteriorate because of freezing. Brick defects and unaligned masonry, deteriorated parapet walls, water-soluble sand lime mortars are probable failure hazard. Wooden beams bear massive weight thus deterioration of the wood in a fire trigger the collapse of the supported masonry structure (Brannigan 1992, p. 157). Cracks signify weak spot in the wall, which may be due to poor foundations. As a result, when one part of the wall pushed, the rest of the wall collapses. An indicator of a wall being pushed out by steel roof beams is a horizontal crack getting longer particularly during the hot season.
Consequently, they contract in winter resulting to unaligned walls. A brick or stone may fell out of an arch thus reducing the stability of the arch. Burned out window or doorframe supporting masonry may collapse due to stress (Brannigan 1992, p. 157).