Charring rate of wood as a tool for fire investigations

Experimental studies on charring of wood are reviewed with the objective of providing guidance for interpretation of char patterns in fire investigations. It is shown that in room fires, the charring rate of wood members that do not have gaps or joints is similar in magnitude to values obtained from fire-resistance tests. But floors and other assemblies having joints that are not solidly glue-laminated char through much more rapidly. Especially rapid charring rates in floor constructions imply high heat fluxes and good ventilation—they are not an indicator that liquid accelerants were used. Fires started with a liquid fuel that do not lead to widespread involvement of other combustibles within the room leave easily recognized burn patterns.