Every medium- and high-rise building should only be clad and insulated with non-combustible* materials.
A building façade can be exposed to flames either from a fire inside the structure that has flashed over (see “What happens in a fire”) and broken through the window; or from a fire in a nearby object such as a trash container or car. What happens next depends on what the façade is made of.
If the façade system, including cladding and/or insulation consist of combustible materials and fire and smoke begin to engulf the building’s façade, it can – depending on the exact material used – rapidly endanger a much greater area of the building and much higher number of building occupants (see also “Fire and smoke toxicity”). In this scenario, the façade adds a significant fuel source to a burning fire. The heat intensity up the side of a building can cause windows to rupture, allowing the fire to spread to more floors.
If on the contrary, the façade consists of non-combustible materials, the flames might eventually reach and breach the windows of the floor above, but the process will be comparatively slow as the façade wouldn’t contribute to the spread of the fire (and resulting smoke). This will leave building occupants more time to escape and the fire brigades more time to extinguish the blaze. This is especially important in medium- and high-rise buildings.
Pieter Maes, Professional Firefighter with the Brussels fire department and Compartment Fire Behaviour Training instructor, puts it this way: “If the fire spreads via the façade to the rest of the building, people are at risk staying in place. Yet if they flee via fire escape routes, that can complicate the fire brigades’ efforts to ascend the same routes to help rescue people and extinguish the fire. That’s why it’s so critical that fires do not spread via building facades. Wrapping buildings – be they residential, offices, schools, or hospitals – in combustible materials risks exactly that”.