What was later determined to be the cause of the floor collapse?

The cause of the floor collapse was determined to be the failure of the "pony wall" due to fire exposure. A pony wall is a short wall that typically supports the structure above it, often used in residential and commercial construction. When exposed to fire, the materials used in such walls can lose their structural integrity.

In fire situations, the intense heat can weaken or compromise the materials, such as wood or drywall, causing structural supports to fail. This would result in a significant risk of collapse, particularly if the loads above (like floors or roofing) exceed what the compromised wall can support. Understanding this failure is crucial for fire safety operations, as it underscores the importance of assessing structural integrity in environments that have been exposed to fire. Recognizing potential points of failure, such as pony walls, helps first responders make informed decisions and prioritize safety when working in these hazardous conditions.