*Since we have no history of fire in a tall raw wood structure is the perception out performing char fire science when it comes to higher risk premiums that remove the competitive edge of mass timber verse steel and concrete?
* How do Fire Marshalls and Fire Figthers feel about tall raw wood mass timber structures with no fire protection during construction is that slowing down the permitting process? Please see video
When certain organic materials are heated, they undergo thermal decomposition and release flammable gases. Flashover occurs when the majority of the exposed surfaces in a space are heated to their autoignition temperature and emit flammable gases.
Flashover is one of the most-feared phenomena among firefighters. Firefighters are taught to recognize the signs and symptoms of rollovers and flashovers and to avoid backdrafts.
A lean flashover (sometimes called rollover) is the ignition of the gas layer under the ceiling, leading to total involvement of the compartment. The fuel/air ratio is at the bottom region of the flammability range (i.e. lean).
A rich flashover occurs when the flammable gases are ignited while at the upper region of the flammability range (i.e. rich). This can happen in rooms where the fire subsided because of lack of oxygen. The ignition source can be a smoulderingobject, or the stirring up of embers by the air track. Such an event is known as 'backdraft'. A delayed flashover occurs when the colder gray smoke cloud ignites after congregating outside of its room of origin. This results in a volatile situation, and if the ignition occurs at the ideal mixture, the result can be a violent smoke gas explosion. This is referred to as smoke explosion or fire gas ignition depending on the severity of the combustion process.
A hot rich flashover occurs when the hot smoke with flammable gas ratio above the upper limit of flammability range and temperature higher than the ignition temperature leaves the compartment. Upon dilution with air it can spontaneously ignite, and the resultant flame can propagate back into the compartment, resulting in an event similar to a rich flashover. The common definition of this process is known as auto-ignition which is another form of fire gas ignition.