The Problem of Glass Failure in Fire

Window glazing is an important element in our built environment. In addition to permitting vision through otherwise opaque walls, windows provide natural lighting and a barrier from the elements.

When exposed to heat from fire ordinary window glass cracks and can be expected to fall from the pane creating an open vent.

The change in ventilation conditions caused by window failure may can result in backdraft or flashover.  In multistory buildings venting flames can result in ignition of upper floors. Glazing is also increasingly used for smoke separation inside buildings.  Failure can result in smoke transmission that may affect the tenability of adjacent smoke cells.

Glazing failure may also result from an external fire exposure.  This results in increased radiant heat transmission into the building and may permit direct flame impingement resulting in fire spread into the building.

Vertical Fire Spread through Windows (Aerial View - Fox News)

Being able to predict when glazing will fail in fire is therefore an important consideration in the fire design of fire smoke cells, fire cells and buildings.  An understanding of why glazing fails can lead to improvements in the design of glazing systems for fire performance and assist in the conduct of fire investigations