The growth of the fire is determined by the type of fuel that is ignited, the heat loss, the rate at which the fuel is being consumed and the ventilation. If there is limited ventilation, the rate of temperature increase will be slower, smoke production will increase due to incomplete combustion and the formation of the smoke layer will be slower. With insufficient oxygen due to the limited ventilation, a flameover might not occur. When the smoke layer leaves through the ventilation source such as a window, it will be seen igniting. For the smoke layer to be maintained and the temperature continue to rise, the fire must be burning energetically enough to overcome the heat loss or a flashover might at occur at all. The amount of fuel necessary to bring a room to flashover can be calculated but the insulation of the room, the height and width of ventilation openings and the volume of the room must be taken into account.
The flashover is not an easily repeatable process. A postflashover fire is one that is controlled by the flow of oxygen. The fire will continue to burn as long as there is sufficient fuel and oxygen. If the flame is extinguished due to insufficient oxygen, it will rekindle as long as fresh air is supplied.
When the fuel in the room is nearly exhausted, the fire eventually dies down and becomes a glowing fire. The fire will continue to combust as long as there is sufficient fuel. The high temperatures may continue as long as there is suitable fuel and the production of the byproducts of incomplete combustion will continue. If there is a sudden supply of fresh oxygen, it might trigger off a flashback, backdraft or smoke explosion due to the ignition of the flammable gas.
One thing to take note is that the smoldering stage may not always be the ending process of a fire. The fire might start off during a smoldering process where the fire source is a slow build of heat until it is able to initiate and sustain combustion,