Layered Excavation
Definition
The systematic removal of fire debris in documented layers, from the surface downward and from low-damage to high-damage areas, to preserve the stratigraphic record of fire development and structural collapse sequence.
- Domain
- Fire scene investigation
- Direction
- Surface downward, low damage to high damage
- Governing guide
- NFPA 921
- Purpose
- Preserve stratigraphic and collapse sequence
Common questions
Why excavate low-damage areas before high-damage ones?+
Working from areas of lesser damage toward areas of greater damage lets the investigator build an understanding of fire spread and intensity gradually, so debris and collapsed material in the most damaged zones can be interpreted against a documented baseline instead of examined in isolation.
What is lost if debris is removed without layering?+
Disturbing the pile out of sequence destroys the stratigraphic record: the order in which materials fell and burned, which can reveal collapse timing, the presence of an ignitable liquid pour pattern, or whether debris was moved before the fire was extinguished.
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