When fires become ventilation limited, what happens to the amount of smoke forced out of structural gaps or openings?

In a ventilation-limited fire, the availability of oxygen to sustain combustion becomes restricted. This limitation results in incomplete combustion of the fuel, producing a greater volume of smoke and other byproducts. However, because the fire is not receiving sufficient oxygen, the conditions alter the flow dynamics of the smoke.

As smoke accumulates inside the structure due to this limited oxygen, the pressure within the building may increase or become stable rather than being able to escape freely through structural gaps or openings. Consequently, the amount of smoke that escapes decreases or may even stop altogether, as the pressure differential that would naturally push smoke out is not strong enough to allow for effective egress.

This behavior underscores the critical relationship between ventilation, fire dynamics, and smoke control during firefighting operations. Proper management of ventilation can help improve smoke control and internal fire conditions, illustrating the importance of understanding these fire behavior principles for effective incident management.