First let me make it perfectly clear that NAFI had nothing to do with the production of this fairy-tale document, was not consulted, and only found out about it from John several weeks ago.

On just a quick read of the material in John’s post, I have found references to seven “old wives’ tales,” thirteen instances of pure bad science, unsupported conjecture, bad methodology, or pseudo-science, and four instances of things that are just wrong or unsupported by research and I never heard of before.

Old Wives’ Tales
-Fire burns up and out.

-A fire that is hot and fast at the point of origin will leave a sharp V pattern. A slow fire will produce a shallow V pattern.

-Fire seeks oxygen. Because fire consumes great amounts of oxygen, it is always drawn toward new sources of oxygen when burning occurs indoors.

-As a general rule, glass that contains many cracks indicates a rapid heat buildup.

-Glass that is heavily stained indicates a slow, smoky fire.

-When wood burns, it chars a pattern of cracks that looks like the scales on an alligator's back. The scales will be the smallest and the cracks the deepest where the fire has been burning the longest or the hottest.

-Most wood in structures chars at the rate of 1 inch in depth per 40 to 45 minutes of burning at 1400° to 1600° Fahrenheit, which is the temperature of most house fires.

Bad Science
-Flame includes both an open flame and a smoldering glow.

-Smoke is composed of very fine solid particles and condensed vapors.

-. The second most dangerous gas produced by a fire is carbon dioxide. While not toxic in itself, a 2 percent increase in carbon dioxide in the air

-If fire meets an obstruction, such as a ceiling, it will burn across the obstruction looking for a place to go up.

-Fire travels with air currents. It never travels into the wind unless the entire fire load, the combustible material or fuel in an area, is on the windward side of the fire. If this happens, the fire slowly eats into the fire load as its tendency to follow the wind is overcome by its attraction for fuel.

-[regarding flashover] But sometimes there are unusual patterns that are the result of a flashover or backdraft,

-[regarding flashover] As the volume of this gas layer increases, it begins to move down to the floor, heating all objects in the room regardless of their proximity to the flaming objects.


-In a typical contained fire, the gas layer at the ceiling can rapidly reach temperatures in excess of its autoignition point. If there is enough existing oxygen, a flashover occurs and everything in the room becomes involved in an open flame all at once.

-[regarding backdraft] Because carbon monoxide is a flammable gas and is heated above its ignition point, it only needs more oxygen to burst into flames.

-Damage caused by a backdraft may look similar to that caused by a low explosive.

-A backdraft produces an unusual char pattern. Most of the burn damage will be at the extreme top of the room. There will also be a rather sharp line of demarcation at the bottom of the char pattern on the wall.

-Bright metals, like the chromium on toasters, turn colors when heated. These colors may remain after the fire and indicate the temperature of the fire at that location.

-Once arson is determined to be the cause of the incident, the investigator will need to obtain specialized equipment to assist with the investigation.


Never heard of:
-A room fire chars only the upper one half to two thirds of the room.

-Ceiling damage in a normal structural fire is usually at least five times the floor damage.

-Sometimes a char pattern has a sharp line of demarcation on one side. This indicates that the fire quit spreading in that direction when a draft entered and blew it back.

- When glass is exposed to fire, it begins to melt at about 1200° Fahrenheit. It becomes runny at about 1600° Fahrenheit

Those who argue that NFPA 921 should not be held as the “standard of care” for fire investigation because there are other texts out there that are just as useful can take heart that this U.S. Army Field Manual is the “standard of care” for the U.S. Army.

Pat Kennedy, CFEI, CFPS, MIFireE
Fire and Explosion Analyst
Sarasota, Florida
[www.kennedy-fire.com]