Cladding and Its Dangers
There are many different types of cladding available, ranging from the traditional looking brickwork or rendered systems to more modern metallic rainscreen systems or curtain walls made from glass. Cladding panels can be made from a wide variety of materials such as wood, metal, brick or vinyl, and are often coupled with composite materials that can include aluminium wood blends of cement and recycled polystyrene wheat rice straw fibres. The most common types of cladding facades that you will hear about on the news, which are a cause for concern are ACM or HPL. ACM (aluminium composite material) façade panels are made up of two aluminium skins bonded to a non aluminium core, often to provide thermal insulation. This is the type of facade panel that was used in the cladding on Grenfell Tower, which caught fire in West London in 2017. HPL (high pressure laminate) facade panels are made by pressurising layers of wood or paper fibres into a resin, and then bonding them together using heat. This is the type of façade panel that was used on the University of Bolton student accommodation block that caught fire in 2019. It is often hard to tell what the material makeup of a cladding system is purely by looking at the facade panels – often, further investigative work will need to be carried out.
In fire safety terms, cladding can be dangerous in a few ways. Firstly, there is the makeup of the cladding system itself. If the cladding system in question contains combustible materials, such as expanded polystyrene (EPS) or polyurethane (PUR), then exposing these materials to a flame will result in fire spread on the outside of a building. This can occur through either a fire breaking out from one of the windows or doorways, through ventilation shafts or from a fire that has occurred on the outside. Fire stopping measures are incorporated into nearly every cladding system – however, some are more effective than others. Many are made using mineral based materials, which are non combustible and highly effective at slowing the spread of fire around the outside of the building. Rainscreen cladding systems require an open cavity to allow the insulation to “breathe” behind the weather resistant cladding panels – however, this is potentially dangerous in a fire, as it creates a chimney for the fire to spread vertically through the building. To allow this, most cavity barriers on the market now incorporate a strip activated by the application of heat which seals the cavity and when applied correctly dramatically slows the vertical spread of fire. This is called an intumescent cavity barrier.
No, cladding is not on every building. However, it is becoming increasingly commonly used on both new build high rises, and older concrete buildings that have been renovated. That said, just because a building has cladding on it does not necessarily mean that it poses a threat to its occupants. There are many different materials used in cladding systems and many modern materials are perfectly safe from a fire spread perspective.
The building regulations were amended in 2018 to implement a ban on combustible building materials on the outside walls of buildings that are taller than 18 metres and contain more than one dwelling. This ban applies to residential housing tower blocks, hospitals, residential care homes, and student accommodation blocks. Fire risk assessments for high-rise tower blocks will also start to include the external walls of a building.
That depends on what your cladding is made from. In most cases, records of the materials that have been used in the construction process are held by the building owners or construction contractor - these will give you an indication of whether or not your building is at risk. If this information is not available, you may have to have a sample of your cladding system tested, in order to determine the materials that it contains, and whether or not there is a potential fire risk. Source: Fire Protection Association
